Re: in-ground clock room
Would the use of a partial vacuum in a sealed chamber or even the septic tank to reach a somewhat steady-state temperature be out of the question, as only radiation would dominate the temperature?
Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might be attainable with a double or triple stacked pettier cooler (reversible in voltage if your outdoor temps get below 0C) with very small tubing with coolant and two tiny DC powered pumps for redundancy with check valves to a small radiator inside the crypt water/ice bath with an RTD temperature sensor. Throw in an above-ground solar and battery backup, and the solid-state refrigeration unit could be fully self-contained and located far enough from the time crypt to not influence gravity, magnetism, quantum physics, etc.
-Jerome Blaha Jr
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Today's Topics:
- Re: in-ground clock room (B Riches)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Andy Gardner, ZL3AG)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Bob kb8tq)
- Re: in-ground clock room (Brent)
- Re: in-ground clock room (Joseph Gwinn)
- Re: in-ground clock room (Steve Allen)
- Re: in-ground clock room (Scott McGrath)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Gilles Clement)
- Re: in-ground clock room (John Marvin)
- Re: [time nuts] Re: in-ground clock room (Bill Beam)
- Re: in-ground clock room (Lux, Jim)
- Re: in-ground clock room (Graham / KE9H)
- Re: in-ground clock room (Ben Bradley)
Message: 1
Date: Thu, 9 Sep 2021 11:17:02 +0000 (UTC)
From: B Riches bill.riches@verizon.net
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com, Tom Van Baak tvb@leapsecond.com
Message-ID: 376021411.3362644.1631186222747@mail.yahoo.com
Content-Type: text/plain; charset=UTF-8
How about using a round septic tank. Mine is about 5 feet wide and 6 feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam wbeam@gci.net wrote:
On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others have pointed out
that a thermal wave of period one year and wave length of several meters propagates
downward thru the soil. Peak amplitude of a few degrees can be expected near the surface.
Consider building an "oven" with the clock vault freely floating in a water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from earth quakes.
But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of entropy.
Protecting the quartz oscillators is much easier than protecting the pendulum clocks.
Bill Beam
NL7F
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Message: 2
Date: Thu, 9 Sep 2021 07:09:33 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpfdjccbGnwncxsSSnGipix9NfcKXD5f3HJjS3eivAqJ6w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
It seems to me that in order to derive much thermal stabilization, the top
of the space would need to be several feet underground (depending on
geographic location). And I think that the means for human access would
likely "spoil the broth" unless fairly extreme measures were taken.
Wouldn't it be sufficient to use a space whose thermal coupling were weak
enough to make the time constant a few days (instead of months)? Then,
ordinary inexpensive means like GPS-locked Rb standards with suitable
(longish) time constants should clean up "GPS noise", yet enable the loop
to take care of low rate temperature variations in the protected space due
to outside temperature changes.
Remember, perfection in clocks is expensive- according to recent things I've
read about entropy of timekeeping, a perfect clock would require infinite
power,
and that alone would blow away all one's efforts at temperature control.
Dana
On Thu, Sep 9, 2021 at 6:19 AM B Riches via time-nuts <
time-nuts@lists.febo.com> wrote:
How about using a round septic tank. Mine is about 5 feet wide and 6
feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <
wbeam@gci.net> wrote:
On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case
walls....
Any ground motion that can be felt will upset the clocks. Often the
clocks will
signal an earth quake that is not felt.
Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others
have pointed out
that a thermal wave of period one year and wave length of several meters
propagates
downward thru the soil. Peak amplitude of a few degrees can be expected
near the surface.
Consider building an "oven" with the clock vault freely floating in a
water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from
earth quakes.
But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of
entropy.
Protecting the quartz oscillators is much easier than protecting the
pendulum clocks.
Bill Beam
NL7F
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Message: 3
Date: Fri, 10 Sep 2021 00:29:15 +1200
From: "Andy Gardner, ZL3AG" zl3ag@radioengineering.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID:
0615ccea-ea7e-a4e3-7c19-8767c37d28e3@radioengineering.com
Content-Type: text/plain; charset=utf-8; format=flowed
So the 2 things you're after are thermal insulation and vibration insulation?
Digging can be expensive, and you have to worry about water table in many locations.
How about the thickest concrete water tank you can find, plonk it in a nice location, spray layers of polyurethane foam over the top and sides for thermal insulation, then build a wind shield ("shed") around it. The shed could be an old coolstore, adding more insulation.
Concrete water tanks are out of fashion these days due to plastics, so if you shop around you can find a cheap used one, and then it's just the trucking/crane charges.
Message: 4
Date: Thu, 9 Sep 2021 07:38:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpdUZSteVrKK_PKfbsCYcJX311TAj7=TBQ7NaYofOpum_w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Tom,
Andy brings up good points, especially about water leaks.
Are you familiar with "Whitlow's 5th law" (which can be summarized
as "everything leaks")?
Dana Whitlow
On Thu, Sep 9, 2021 at 7:29 AM Andy Gardner, ZL3AG via time-nuts <
time-nuts@lists.febo.com> wrote:
So the 2 things you're after are thermal insulation and vibration
insulation?
Digging can be expensive, and you have to worry about water table in many
locations.
How about the thickest concrete water tank you can find, plonk it in a
nice location, spray layers of polyurethane foam over the top and sides for
thermal insulation, then build a wind shield ("shed") around it. The shed
could be an old coolstore, adding more insulation.
Concrete water tanks are out of fashion these days due to plastics, so if
you shop around you can find a cheap used one, and then it's just the
trucking/crane charges.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 5
Date: Thu, 9 Sep 2021 09:04:04 -0400
From: Bob kb8tq kb8tq@n1k.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Cc: Tom Van Baak tvb@LeapSecond.com
Message-ID: E624E63E-7BCD-49E8-9AF5-FF9C7C32E02B@n1k.org
Content-Type: text/plain; charset=utf-8
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
https://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Message: 6
Date: Thu, 9 Sep 2021 10:12:06 -0400
From: Brent brent.evers@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAP6i9Mni5LDGDaanNB5QP=SHtYErLQURBknu7iVo6CHaxaSPdA@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).
I've been in various seismic vaults and they can vary from very extravagant
to downright crude.
On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
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an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 7
Date: Thu, 9 Sep 2021 12:02:44 -0400
From: Joseph Gwinn joegwinn@comcast.net
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 20210909120244341063.4dfa1be6@comcast.net
Content-Type: text/plain; charset=iso-8859-1
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
Message: 8
Date: Thu, 9 Sep 2021 09:13:18 -0700
From: Steve Allen sla@ucolick.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 20210909161318.GA19164@ucolick.org
Content-Type: text/plain; charset=utf-8
On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ:
I am considering a below ground "clock room" away from the house. This will
be for some low-drift quartz oscillators and also a couple of precision
pendulum clocks. The goal is long-term, unattended, and very undisturbed
operation.
How deep?
Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment,
facilities, and operations of Bureau International de l'Heure at
Observatoire de Paris.
The highest precision pendulum clocks, the ones which had mechanisms
to correct for temperature and pressure (the "garde-temps") were kept
27 m below ground in caves and galleries which were part of the
Paris catacombs.
Various issues of Bulletin Horaire report discontinuities in the
operation of those clocks due to distant earthquakes.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 https://url.emailprotection.link/?babImg0bEUxMHpPsxOmCp3Cn-KMvw54w86vJHHj3bTiz-n20wRlflI_23_p5IjE256VI1iFbNSdl2v6Rv0dqwQw~~ Hgt +250 m
Message: 9
Date: Thu, 9 Sep 2021 12:28:00 -0400
From: Scott McGrath scmcgrath@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 0595152C-C512-45D9-8903-F2616D349B59@gmail.com
Content-Type: text/plain; charset=utf-8
Rather than custom casting a structure you might want to consider use of a precast concrete septic tank or transformer vault as cost will be much lower.
You will also need to consider waterproofing the tank it already has a layer of waterproofing but a couple of additional layers will probably be necessary as well as ensuring proper drainage around it as it will need to be both above local water table and be able to drain off percolating rainwater.
You will also need to control temperature and humidity
On Sep 9, 2021, at 12:03 PM, Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 10
Date: Thu, 9 Sep 2021 11:35:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpffWGTpaX+s02YfnEx704RP_5rWgxheFFjAb+ALf8iQEQ@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.
Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
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Message: 11
Date: Thu, 9 Sep 2021 21:05:11 +0200
From: Gilles Clement clemgill@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: C3B65D1E-3EB2-42F0-8291-46EBA92DD8CA@gmail.com
Content-Type: text/plain; charset=utf-8
With a slight cantilevered cavity at the base,
instrumental as a *nut cracker… o:))
- = time?
Le 9 sept. 2021 à 18:35, Dana Whitlow k8yumdoober@gmail.com a écrit :
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.
Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
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Message: 12
Date: Thu, 9 Sep 2021 13:57:44 -0600
From: John Marvin jm-tnut@themarvins.org
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 7c02f7ff-8cd7-e2b2-88af-16f6ee138466@themarvins.org
Content-Type: text/plain; charset=utf-8; format=flowed
Hmm, this list isn't called time-science, time-research, time-hardware,
or time-trivia. It's called time-nuts. This is probably one of the most
on topic (and fun) posts I've seen on this list. :)
Regards,
John
On 9/8/2021 7:54 PM, Tom Van Baak wrote:
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
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Message: 13
Date: Thu, 09 Sep 2021 13:57:30 -0800
From: "Bill Beam" wbeam@gci.net
Subject: [time-nuts] Re: [time nuts] Re: in-ground clock room
To: "Discussion of precise time and frequency measurement"
time-nuts@lists.febo.com
Message-ID: 05.1F.05200.1538A316@smtp02.beryl.bos.sync.lan
Content-Type: text/plain; charset="us-ascii"
--Original Message Text---
From: Tom Van Baak
Date: Thu, 9 Sep 2021 04:44:22 -0700
Hi Bill,
I'd like undisturbed on the order of several months or years. Yes, earthquakes are possible but they are rare here and interesting so that's
ok. Here's a once-in-a-decade one that I captured a few years ago:
The main thing is to avoid "cultural noise" -- local seismic activity caused by cars, trucks, doors opening and closing, people walking, A/C or
mechanical appliances going on and off, etc. This is best done by locating the clocks away from roads, away from the house, in a solid
compartment weighing many tons, underground in virgin soil or bedrock.
Hi Tom,
A "compartment weighing many tons" is a low pass filter good against "cultural noise" but not so good against earth quake or earth tide
noise. A "compartment weighing many tons" is strongly coupled to the earth. The opposite approach is to uncouple from the earth as
much as possible. Your earthquake enviornment in the Pacific northwest is similar to here in Alaska. Your precision pendulum clock
is good enough to respond to monthly/daily earth tides. There is a 'catch 22' in trying to protect a pendulum clock. The pendulum
depends on constant acceleration of gravity. It ain't constant. If g varies or is noisy by one part in N then that sets the point of diminishing
return in your protection efforts.
Bill
/tvb
On 9/8/2021 7:36 PM, Bill Beam wrote:
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
Bill Beam
NL7F
Bill Beam
NL7F
Message: 14
Date: Thu, 9 Sep 2021 15:17:22 -0700
From: "Lux, Jim" jim@luxfamily.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: dbb895a4-371c-81bb-2ae0-7a982274642d@luxfamily.com
Content-Type: text/plain; charset=utf-8; format=flowed
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).
For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).
I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.
The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.
Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.
Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.
Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week
https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000
One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)
One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.
The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
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Message: 15
Date: Thu, 9 Sep 2021 18:03:08 -0500
From: "Graham / KE9H" ke9h.graham@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAPyJ-YWhz_C7r=meJ91skKMeQtBA7rRXVKZAtByCA3cARqo_Qw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Sounds like we need a volunteer time-nut with motion picture camera
capability to document this event.
--- Graham
On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim jim@luxfamily.com wrote:
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).
For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).
I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.
The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.
Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.
Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.
Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week
https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000
One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)
One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.
The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
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Message: 16
Date: Thu, 9 Sep 2021 20:47:29 -0400
From: Ben Bradley ben.pi.bradley@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CA+wjhVsKT67AOghjXT91LwupF0FG3v=XiQEX4q0-2jVRQYHXnw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
I've seen discussion of making a seismic vault (though not sure if
they used that name, making it harder to find in the haystack of
posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if
this is helpful:
https://url.emailprotection.link/?bj4D6X82wPC9xeltcsFCTXzK_O0xDS6ilwrNrr973O-CWyDkiYmR6AtIlije3Uhl-EhDjaWB722xAQMGo5pYzKsypwE_cPrdr7cPkFE8GrFQ48neYZCy5Hu7yuZjpSqlB
For possible immunity from earthquakes, LIGO uses some quite complex
control and feedback systems to hang its mirrors so that mild
earthquakes and local noise won't affect them. From what I've seen
over the years a lot of this info has been published, but I imagine it
would be quite expensive to reproduce. Maybe some sort of Ligo Lite
system would be feasible.
On Thu, Sep 9, 2021 at 10:13 AM Brent brent.evers@gmail.com wrote:
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).
I've been in various seismic vaults and they can vary from very extravagant
to downright crude.
On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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End of time-nuts Digest, Vol 209, Issue 7
Hi
I think that if you are looking at something this size, a compressor based heat / cool setup
will do much better than a solid state approach. Way less power due to the much better
efficiency . You can get pretty small systems that will hold < 0.05 C on the “coolant line".
Bob
On Sep 10, 2021, at 5:03 PM, Jerome Blaha jblaha@polariswireless.com wrote:
Would the use of a partial vacuum in a sealed chamber or even the septic tank to reach a somewhat steady-state temperature be out of the question, as only radiation would dominate the temperature?
Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might be attainable with a double or triple stacked pettier cooler (reversible in voltage if your outdoor temps get below 0C) with very small tubing with coolant and two tiny DC powered pumps for redundancy with check valves to a small radiator inside the crypt water/ice bath with an RTD temperature sensor. Throw in an above-ground solar and battery backup, and the solid-state refrigeration unit could be fully self-contained and located far enough from the time crypt to not influence gravity, magnetism, quantum physics, etc.
-Jerome Blaha Jr
-----Original Message-----
From: time-nuts-request@lists.febo.com [mailto:time-nuts-request@lists.febo.com]
Sent: Friday, September 10, 2021 12:30 AM
To: time-nuts@lists.febo.com
Subject: time-nuts Digest, Vol 209, Issue 7
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Today's Topics:
- Re: in-ground clock room (B Riches)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Andy Gardner, ZL3AG)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Bob kb8tq)
- Re: in-ground clock room (Brent)
- Re: in-ground clock room (Joseph Gwinn)
- Re: in-ground clock room (Steve Allen)
- Re: in-ground clock room (Scott McGrath)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Gilles Clement)
- Re: in-ground clock room (John Marvin)
- Re: [time nuts] Re: in-ground clock room (Bill Beam)
- Re: in-ground clock room (Lux, Jim)
- Re: in-ground clock room (Graham / KE9H)
- Re: in-ground clock room (Ben Bradley)
Message: 1
Date: Thu, 9 Sep 2021 11:17:02 +0000 (UTC)
From: B Riches bill.riches@verizon.net
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com, Tom Van Baak tvb@leapsecond.com
Message-ID: 376021411.3362644.1631186222747@mail.yahoo.com
Content-Type: text/plain; charset=UTF-8
How about using a round septic tank. Mine is about 5 feet wide and 6 feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam wbeam@gci.net wrote:
On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others have pointed out
that a thermal wave of period one year and wave length of several meters propagates
downward thru the soil. Peak amplitude of a few degrees can be expected near the surface.
Consider building an "oven" with the clock vault freely floating in a water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from earth quakes.
But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of entropy.
Protecting the quartz oscillators is much easier than protecting the pendulum clocks.
Bill Beam
NL7F
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Message: 2
Date: Thu, 9 Sep 2021 07:09:33 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpfdjccbGnwncxsSSnGipix9NfcKXD5f3HJjS3eivAqJ6w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
It seems to me that in order to derive much thermal stabilization, the top
of the space would need to be several feet underground (depending on
geographic location). And I think that the means for human access would
likely "spoil the broth" unless fairly extreme measures were taken.
Wouldn't it be sufficient to use a space whose thermal coupling were weak
enough to make the time constant a few days (instead of months)? Then,
ordinary inexpensive means like GPS-locked Rb standards with suitable
(longish) time constants should clean up "GPS noise", yet enable the loop
to take care of low rate temperature variations in the protected space due
to outside temperature changes.
Remember, perfection in clocks is expensive- according to recent things I've
read about entropy of timekeeping, a perfect clock would require infinite
power,
and that alone would blow away all one's efforts at temperature control.
Dana
On Thu, Sep 9, 2021 at 6:19 AM B Riches via time-nuts <
time-nuts@lists.febo.com> wrote:
How about using a round septic tank. Mine is about 5 feet wide and 6
feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <
wbeam@gci.net> wrote:
On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case
walls....
Any ground motion that can be felt will upset the clocks. Often the
clocks will
signal an earth quake that is not felt.
Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others
have pointed out
that a thermal wave of period one year and wave length of several meters
propagates
downward thru the soil. Peak amplitude of a few degrees can be expected
near the surface.
Consider building an "oven" with the clock vault freely floating in a
water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from
earth quakes.
But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of
entropy.
Protecting the quartz oscillators is much easier than protecting the
pendulum clocks.
Bill Beam
NL7F
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
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Message: 3
Date: Fri, 10 Sep 2021 00:29:15 +1200
From: "Andy Gardner, ZL3AG" zl3ag@radioengineering.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID:
0615ccea-ea7e-a4e3-7c19-8767c37d28e3@radioengineering.com
Content-Type: text/plain; charset=utf-8; format=flowed
So the 2 things you're after are thermal insulation and vibration insulation?
Digging can be expensive, and you have to worry about water table in many locations.
How about the thickest concrete water tank you can find, plonk it in a nice location, spray layers of polyurethane foam over the top and sides for thermal insulation, then build a wind shield ("shed") around it. The shed could be an old coolstore, adding more insulation.
Concrete water tanks are out of fashion these days due to plastics, so if you shop around you can find a cheap used one, and then it's just the trucking/crane charges.
Message: 4
Date: Thu, 9 Sep 2021 07:38:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpdUZSteVrKK_PKfbsCYcJX311TAj7=TBQ7NaYofOpum_w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Tom,
Andy brings up good points, especially about water leaks.
Are you familiar with "Whitlow's 5th law" (which can be summarized
as "everything leaks")?
Dana Whitlow
On Thu, Sep 9, 2021 at 7:29 AM Andy Gardner, ZL3AG via time-nuts <
time-nuts@lists.febo.com> wrote:
So the 2 things you're after are thermal insulation and vibration
insulation?
Digging can be expensive, and you have to worry about water table in many
locations.
How about the thickest concrete water tank you can find, plonk it in a
nice location, spray layers of polyurethane foam over the top and sides for
thermal insulation, then build a wind shield ("shed") around it. The shed
could be an old coolstore, adding more insulation.
Concrete water tanks are out of fashion these days due to plastics, so if
you shop around you can find a cheap used one, and then it's just the
trucking/crane charges.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 5
Date: Thu, 9 Sep 2021 09:04:04 -0400
From: Bob kb8tq kb8tq@n1k.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Cc: Tom Van Baak tvb@LeapSecond.com
Message-ID: E624E63E-7BCD-49E8-9AF5-FF9C7C32E02B@n1k.org
Content-Type: text/plain; charset=utf-8
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
https://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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To unsubscribe, go to and follow the instructions there.
Message: 6
Date: Thu, 9 Sep 2021 10:12:06 -0400
From: Brent brent.evers@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAP6i9Mni5LDGDaanNB5QP=SHtYErLQURBknu7iVo6CHaxaSPdA@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).
I've been in various seismic vaults and they can vary from very extravagant
to downright crude.
On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
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an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 7
Date: Thu, 9 Sep 2021 12:02:44 -0400
From: Joseph Gwinn joegwinn@comcast.net
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 20210909120244341063.4dfa1be6@comcast.net
Content-Type: text/plain; charset=iso-8859-1
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
Message: 8
Date: Thu, 9 Sep 2021 09:13:18 -0700
From: Steve Allen sla@ucolick.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 20210909161318.GA19164@ucolick.org
Content-Type: text/plain; charset=utf-8
On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ:
I am considering a below ground "clock room" away from the house. This will
be for some low-drift quartz oscillators and also a couple of precision
pendulum clocks. The goal is long-term, unattended, and very undisturbed
operation.
How deep?
Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment,
facilities, and operations of Bureau International de l'Heure at
Observatoire de Paris.
The highest precision pendulum clocks, the ones which had mechanisms
to correct for temperature and pressure (the "garde-temps") were kept
27 m below ground in caves and galleries which were part of the
Paris catacombs.
Various issues of Bulletin Horaire report discontinuities in the
operation of those clocks due to distant earthquakes.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 https://url.emailprotection.link/?babImg0bEUxMHpPsxOmCp3Cn-KMvw54w86vJHHj3bTiz-n20wRlflI_23_p5IjE256VI1iFbNSdl2v6Rv0dqwQw~~ Hgt +250 m
Message: 9
Date: Thu, 9 Sep 2021 12:28:00 -0400
From: Scott McGrath scmcgrath@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 0595152C-C512-45D9-8903-F2616D349B59@gmail.com
Content-Type: text/plain; charset=utf-8
Rather than custom casting a structure you might want to consider use of a precast concrete septic tank or transformer vault as cost will be much lower.
You will also need to consider waterproofing the tank it already has a layer of waterproofing but a couple of additional layers will probably be necessary as well as ensuring proper drainage around it as it will need to be both above local water table and be able to drain off percolating rainwater.
You will also need to control temperature and humidity
On Sep 9, 2021, at 12:03 PM, Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 10
Date: Thu, 9 Sep 2021 11:35:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpffWGTpaX+s02YfnEx704RP_5rWgxheFFjAb+ALf8iQEQ@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.
Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Message: 11
Date: Thu, 9 Sep 2021 21:05:11 +0200
From: Gilles Clement clemgill@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: C3B65D1E-3EB2-42F0-8291-46EBA92DD8CA@gmail.com
Content-Type: text/plain; charset=utf-8
With a slight cantilevered cavity at the base,
instrumental as a *nut cracker… o:))
- = time?
Le 9 sept. 2021 à 18:35, Dana Whitlow k8yumdoober@gmail.com a écrit :
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.
Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowed
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
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Message: 12
Date: Thu, 9 Sep 2021 13:57:44 -0600
From: John Marvin jm-tnut@themarvins.org
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 7c02f7ff-8cd7-e2b2-88af-16f6ee138466@themarvins.org
Content-Type: text/plain; charset=utf-8; format=flowed
Hmm, this list isn't called time-science, time-research, time-hardware,
or time-trivia. It's called time-nuts. This is probably one of the most
on topic (and fun) posts I've seen on this list. :)
Regards,
John
On 9/8/2021 7:54 PM, Tom Van Baak wrote:
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
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Message: 13
Date: Thu, 09 Sep 2021 13:57:30 -0800
From: "Bill Beam" wbeam@gci.net
Subject: [time-nuts] Re: [time nuts] Re: in-ground clock room
To: "Discussion of precise time and frequency measurement"
time-nuts@lists.febo.com
Message-ID: 05.1F.05200.1538A316@smtp02.beryl.bos.sync.lan
Content-Type: text/plain; charset="us-ascii"
--Original Message Text---
From: Tom Van Baak
Date: Thu, 9 Sep 2021 04:44:22 -0700
Hi Bill,
I'd like undisturbed on the order of several months or years. Yes, earthquakes are possible but they are rare here and interesting so that's
ok. Here's a once-in-a-decade one that I captured a few years ago:
The main thing is to avoid "cultural noise" -- local seismic activity caused by cars, trucks, doors opening and closing, people walking, A/C or
mechanical appliances going on and off, etc. This is best done by locating the clocks away from roads, away from the house, in a solid
compartment weighing many tons, underground in virgin soil or bedrock.
Hi Tom,
A "compartment weighing many tons" is a low pass filter good against "cultural noise" but not so good against earth quake or earth tide
noise. A "compartment weighing many tons" is strongly coupled to the earth. The opposite approach is to uncouple from the earth as
much as possible. Your earthquake enviornment in the Pacific northwest is similar to here in Alaska. Your precision pendulum clock
is good enough to respond to monthly/daily earth tides. There is a 'catch 22' in trying to protect a pendulum clock. The pendulum
depends on constant acceleration of gravity. It ain't constant. If g varies or is noisy by one part in N then that sets the point of diminishing
return in your protection efforts.
Bill
/tvb
On 9/8/2021 7:36 PM, Bill Beam wrote:
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
Bill Beam
NL7F
Bill Beam
NL7F
Message: 14
Date: Thu, 9 Sep 2021 15:17:22 -0700
From: "Lux, Jim" jim@luxfamily.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: dbb895a4-371c-81bb-2ae0-7a982274642d@luxfamily.com
Content-Type: text/plain; charset=utf-8; format=flowed
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).
For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).
I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.
The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.
Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.
Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.
Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week
https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000
One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)
One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.
The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
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Message: 15
Date: Thu, 9 Sep 2021 18:03:08 -0500
From: "Graham / KE9H" ke9h.graham@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAPyJ-YWhz_C7r=meJ91skKMeQtBA7rRXVKZAtByCA3cARqo_Qw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Sounds like we need a volunteer time-nut with motion picture camera
capability to document this event.
--- Graham
On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim jim@luxfamily.com wrote:
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).
For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).
I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.
The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.
Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.
Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.
Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week
https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000
One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)
One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.
The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
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send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
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Message: 16
Date: Thu, 9 Sep 2021 20:47:29 -0400
From: Ben Bradley ben.pi.bradley@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CA+wjhVsKT67AOghjXT91LwupF0FG3v=XiQEX4q0-2jVRQYHXnw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
I've seen discussion of making a seismic vault (though not sure if
they used that name, making it harder to find in the haystack of
posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if
this is helpful:
https://url.emailprotection.link/?bj4D6X82wPC9xeltcsFCTXzK_O0xDS6ilwrNrr973O-CWyDkiYmR6AtIlije3Uhl-EhDjaWB722xAQMGo5pYzKsypwE_cPrdr7cPkFE8GrFQ48neYZCy5Hu7yuZjpSqlB
For possible immunity from earthquakes, LIGO uses some quite complex
control and feedback systems to hang its mirrors so that mild
earthquakes and local noise won't affect them. From what I've seen
over the years a lot of this info has been published, but I imagine it
would be quite expensive to reproduce. Maybe some sort of Ligo Lite
system would be feasible.
On Thu, Sep 9, 2021 at 10:13 AM Brent brent.evers@gmail.com wrote:
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).
I've been in various seismic vaults and they can vary from very extravagant
to downright crude.
On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.
I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.
In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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On Fri, 10 Sep 2021 21:03:05 +0000, Jerome Blaha wrote:
Would the use of a partial vacuum in a sealed chamber or even the septic tank to reach a somewhat steady-state temperature be out of the
question, as only radiation would dominate the temperature?
Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might be attainable with a double or triple stacked pettier cooler
(reversible in voltage if your outdoor temps get below 0C) with very small tubing with coolant and two tiny DC powered pumps for redundancy
with check valves to a small radiator inside the crypt water/ice bath with an RTD temperature sensor. Throw in an above-ground solar and
battery backup, and the solid-state refrigeration unit could be fully self-contained and located far enough from the time crypt to not influence
gravity, magnetism, quantum physics, etc.
My suggestion of floating the clock in a water/ice bath raises a not so obvious mechanical issue: The clock is now no longer constrained
against side-to-side motion. As the pendulum swings to and fro the clock case will move/rock fro and to. Expect large phase noise from
turbulence in the bath.
A 'simple' pendulum exists only in theory. A real 'simple' pendulum does not exist in any ones clock lab.
Bill Beam
NL7F
Bill Beam writes:
Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might
be attainable with a double or triple stacked pettier cooler [...]
There are excellent and cheap, widely available cabinets for this kind of
experiment: Buy a fridge or a freezer and dont plug it in.
If you want to, you can use the plumbing to run your own cooleant.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Magnetic levitation, dampening external vibrations ?
GC
Le 10 sept. 2021 à 23:03, Jerome Blaha jblaha@polariswireless.com a écrit :
Would the use of a partial vacuum in a sealed chamber or even the septic tank to reach a somewhat steady-state temperature be out of the question, as only radiation would dominate the temperature?
Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might be attainable with a double or triple stacked pettier cooler (reversible in voltage if your outdoor temps get below 0C) with very small tubing with coolant and two tiny DC powered pumps for redundancy with check valves to a small radiator inside the crypt water/ice bath with an RTD temperature sensor. Throw in an above-ground solar and battery backup, and the solid-state refrigeration unit could be fully self-contained and located far enough from the time crypt to not influence gravity, magnetism, quantum physics, etc.
-Jerome Blaha Jr
-----Original Message-----
From: time-nuts-request@lists.febo.com [mailto:time-nuts-request@lists.febo.com]
Sent: Friday, September 10, 2021 12:30 AM
To: time-nuts@lists.febo.com
Subject: time-nuts Digest, Vol 209, Issue 7
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Today's Topics:
- Re: in-ground clock room (B Riches)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Andy Gardner, ZL3AG)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Bob kb8tq)
- Re: in-ground clock room (Brent)
- Re: in-ground clock room (Joseph Gwinn)
- Re: in-ground clock room (Steve Allen)
- Re: in-ground clock room (Scott McGrath)
- Re: in-ground clock room (Dana Whitlow)
- Re: in-ground clock room (Gilles Clement)
- Re: in-ground clock room (John Marvin)
- Re: [time nuts] Re: in-ground clock room (Bill Beam)
- Re: in-ground clock room (Lux, Jim)
- Re: in-ground clock room (Graham / KE9H)
- Re: in-ground clock room (Ben Bradley)
Message: 1
Date: Thu, 9 Sep 2021 11:17:02 +0000 (UTC)
From: B Riches bill.riches@verizon.net
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com, Tom Van Baak tvb@leapsecond.com
Message-ID: 376021411.3362644.1631186222747@mail.yahoo.com
Content-Type: text/plain; charset=UTF-8
How about using a round septic tank. Mine is about 5 feet wide and 6 feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam wbeam@gci.net wrote:
On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.
For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.
If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
Thanks,
/tvb
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others have pointed out
that a thermal wave of period one year and wave length of several meters propagates
downward thru the soil. Peak amplitude of a few degrees can be expected near the surface.
Consider building an "oven" with the clock vault freely floating in a water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from earth quakes.
But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of entropy.
Protecting the quartz oscillators is much easier than protecting the pendulum clocks.
Bill Beam
NL7F
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Message: 2
Date: Thu, 9 Sep 2021 07:09:33 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpfdjccbGnwncxsSSnGipix9NfcKXD5f3HJjS3eivAqJ6w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
It seems to me that in order to derive much thermal stabilization, the top
of the space would need to be several feet underground (depending on
geographic location). And I think that the means for human access would
likely "spoil the broth" unless fairly extreme measures were taken.
Wouldn't it be sufficient to use a space whose thermal coupling were weak
enough to make the time constant a few days (instead of months)? Then,
ordinary inexpensive means like GPS-locked Rb standards with suitable
(longish) time constants should clean up "GPS noise", yet enable the loop
to take care of low rate temperature variations in the protected space due
to outside temperature changes.
Remember, perfection in clocks is expensive- according to recent things I've
read about entropy of timekeeping, a perfect clock would require infinite
power,
and that alone would blow away all one's efforts at temperature control.
Dana
On Thu, Sep 9, 2021 at 6:19 AM B Riches via time-nuts <
time-nuts@lists.febo.com> wrote:
How about using a round septic tank. Mine is about 5 feet wide and 6
feet deep Large hole in the top - put ladder for entry.
73,
Bill, WA2DVUCape May, NJ
On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <
wbeam@gci.net> wrote:On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter +— 1 meter +— 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).Thanks,
/tvbTom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case
walls....
Any ground motion that can be felt will upset the clocks. Often the
clocks will
signal an earth quake that is not felt.Good luck.
I spent a few years as a geotechnic/soils engineer and learned as others
have pointed out
that a thermal wave of period one year and wave length of several meters
propagates
downward thru the soil. Peak amplitude of a few degrees can be expected
near the surface.Consider building an "oven" with the clock vault freely floating in a
water-ice mixture. This will
provide constant temperature (0C) and limited mechanical isolation from
earth quakes.But of course this will be expensive to operate.
As you know 'good' clocks require a lot of energy and generate a lot of
entropy.Protecting the quartz oscillators is much easier than protecting the
pendulum clocks.Bill Beam
NL7F
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Message: 3
Date: Fri, 10 Sep 2021 00:29:15 +1200
From: "Andy Gardner, ZL3AG" zl3ag@radioengineering.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID:
0615ccea-ea7e-a4e3-7c19-8767c37d28e3@radioengineering.com
Content-Type: text/plain; charset=utf-8; format=flowed
So the 2 things you're after are thermal insulation and vibration insulation?
Digging can be expensive, and you have to worry about water table in many locations.
How about the thickest concrete water tank you can find, plonk it in a nice location, spray layers of polyurethane foam over the top and sides for thermal insulation, then build a wind shield ("shed") around it. The shed could be an old coolstore, adding more insulation.
Concrete water tanks are out of fashion these days due to plastics, so if you shop around you can find a cheap used one, and then it's just the trucking/crane charges.
Message: 4
Date: Thu, 9 Sep 2021 07:38:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpdUZSteVrKK_PKfbsCYcJX311TAj7=TBQ7NaYofOpum_w@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Tom,
Andy brings up good points, especially about water leaks.
Are you familiar with "Whitlow's 5th law" (which can be summarized
as "everything leaks")?
Dana Whitlow
On Thu, Sep 9, 2021 at 7:29 AM Andy Gardner, ZL3AG via time-nuts <
time-nuts@lists.febo.com> wrote:
So the 2 things you're after are thermal insulation and vibration
insulation?Digging can be expensive, and you have to worry about water table in many
locations.How about the thickest concrete water tank you can find, plonk it in a
nice location, spray layers of polyurethane foam over the top and sides for
thermal insulation, then build a wind shield ("shed") around it. The shed
could be an old coolstore, adding more insulation.Concrete water tanks are out of fashion these days due to plastics, so if
you shop around you can find a cheap used one, and then it's just the
trucking/crane charges.
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Message: 5
Date: Thu, 9 Sep 2021 09:04:04 -0400
From: Bob kb8tq kb8tq@n1k.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Cc: Tom Van Baak tvb@LeapSecond.com
Message-ID: E624E63E-7BCD-49E8-9AF5-FF9C7C32E02B@n1k.org
Content-Type: text/plain; charset=utf-8
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….
How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the geology,
part is how the builder graded things to put in the subdivision.
While that sounds ideal, the shale is tilted due to some thing running into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.
Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a very
different situation. (again thanks to just how this ran into that ….).
Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...
Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Message: 6
Date: Thu, 9 Sep 2021 10:12:06 -0400
From: Brent brent.evers@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAP6i9Mni5LDGDaanNB5QP=SHtYErLQURBknu7iVo6CHaxaSPdA@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).
I've been in various seismic vaults and they can vary from very extravagant
to downright crude.
On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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Message: 7
Date: Thu, 9 Sep 2021 12:02:44 -0400
From: Joseph Gwinn joegwinn@comcast.net
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 20210909120244341063.4dfa1be6@comcast.net
Content-Type: text/plain; charset=iso-8859-1
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowedI am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
Message: 8
Date: Thu, 9 Sep 2021 09:13:18 -0700
From: Steve Allen sla@ucolick.org
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 20210909161318.GA19164@ucolick.org
Content-Type: text/plain; charset=utf-8
On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ:
I am considering a below ground "clock room" away from the house. This will
be for some low-drift quartz oscillators and also a couple of precision
pendulum clocks. The goal is long-term, unattended, and very undisturbed
operation.
How deep?
Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment,
facilities, and operations of Bureau International de l'Heure at
Observatoire de Paris.
The highest precision pendulum clocks, the ones which had mechanisms
to correct for temperature and pressure (the "garde-temps") were kept
27 m below ground in caves and galleries which were part of the
Paris catacombs.
Various issues of Bulletin Horaire report discontinuities in the
operation of those clocks due to distant earthquakes.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 https://url.emailprotection.link/?babImg0bEUxMHpPsxOmCp3Cn-KMvw54w86vJHHj3bTiz-n20wRlflI_23_p5IjE256VI1iFbNSdl2v6Rv0dqwQw~~ Hgt +250 m
Message: 9
Date: Thu, 9 Sep 2021 12:28:00 -0400
From: Scott McGrath scmcgrath@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 0595152C-C512-45D9-8903-F2616D349B59@gmail.com
Content-Type: text/plain; charset=utf-8
Rather than custom casting a structure you might want to consider use of a precast concrete septic tank or transformer vault as cost will be much lower.
You will also need to consider waterproofing the tank it already has a layer of waterproofing but a couple of additional layers will probably be necessary as well as ensuring proper drainage around it as it will need to be both above local water table and be able to drain off percolating rainwater.
You will also need to control temperature and humidity
On Sep 9, 2021, at 12:03 PM, Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowedI am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).
As others have said, it may not be economically practical to build an
underground clock room.
Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.
This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.
Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.
Joe Gwinn
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To unsubscribe, go to and follow the instructions there.
Message: 10
Date: Thu, 9 Sep 2021 11:35:30 -0500
From: Dana Whitlow k8yumdoober@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CADHrwpffWGTpaX+s02YfnEx704RP_5rWgxheFFjAb+ALf8iQEQ@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.
Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowedI am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).As others have said, it may not be economically practical to build an
underground clock room.Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
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To unsubscribe, go to and follow the instructions there.
Message: 11
Date: Thu, 9 Sep 2021 21:05:11 +0200
From: Gilles Clement clemgill@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: C3B65D1E-3EB2-42F0-8291-46EBA92DD8CA@gmail.com
Content-Type: text/plain; charset=utf-8
With a slight cantilevered cavity at the base,
instrumental as a *nut cracker… o:))
- = time?
Le 9 sept. 2021 à 18:35, Dana Whitlow k8yumdoober@gmail.com a écrit :
One might also consider mounting smaller items inside the cylinders of the
engine block,
to get the most out of its thermal mass.Dana
On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn joegwinn@comcast.net wrote:
On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request@lists.febo.com
wrote:
Re: time-nuts Digest, Vol 209, Issue 6
Date: Wed, 8 Sep 2021 18:54:03 -0700
From: Tom Van Baak tvb@LeapSecond.com
Subject: [time-nuts] in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID: 4037f6cb-ade3-8c01-8c36-7edf193274d6@LeapSecond.com
Content-Type: text/plain; charset=utf-8; format=flowedI am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).As others have said, it may not be economically practical to build an
underground clock room.Assuming that you have a basement of other suitable room in your
house, I'd suggest an insulated box or room containing a big lump of
iron riding on an inner-tube suspension of some kind. The big lump
of iron can be a 500-pound truck engine head or block from a
junkyard, steam cleaned (to remove oil) and painted (to keep the rust
under control). Drill and tap holes as needed for mounting.This box/room plus block can be set up as a temperature-controlled
oven with a few extra components, including a PID controller.Bolt a thick plywood floor to the top of the iron hunk, and attach
the clocks to this floor.Joe Gwinn
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
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Message: 12
Date: Thu, 9 Sep 2021 13:57:44 -0600
From: John Marvin jm-tnut@themarvins.org
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: 7c02f7ff-8cd7-e2b2-88af-16f6ee138466@themarvins.org
Content-Type: text/plain; charset=utf-8; format=flowed
Hmm, this list isn't called time-science, time-research, time-hardware,
or time-trivia. It's called time-nuts. This is probably one of the most
on topic (and fun) posts I've seen on this list. :)
Regards,
John
On 9/8/2021 7:54 PM, Tom Van Baak wrote:
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).Thanks,
/tvb
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Message: 13
Date: Thu, 09 Sep 2021 13:57:30 -0800
From: "Bill Beam" wbeam@gci.net
Subject: [time-nuts] Re: [time nuts] Re: in-ground clock room
To: "Discussion of precise time and frequency measurement"
time-nuts@lists.febo.com
Message-ID: 05.1F.05200.1538A316@smtp02.beryl.bos.sync.lan
Content-Type: text/plain; charset="us-ascii"
--Original Message Text---
From: Tom Van Baak
Date: Thu, 9 Sep 2021 04:44:22 -0700
Hi Bill,
I'd like undisturbed on the order of several months or years. Yes, earthquakes are possible but they are rare here and interesting so that's
ok. Here's a once-in-a-decade one that I captured a few years ago:
The main thing is to avoid "cultural noise" -- local seismic activity caused by cars, trucks, doors opening and closing, people walking, A/C or
mechanical appliances going on and off, etc. This is best done by locating the clocks away from roads, away from the house, in a solid
compartment weighing many tons, underground in virgin soil or bedrock.
Hi Tom,
A "compartment weighing many tons" is a low pass filter good against "cultural noise" but not so good against earth quake or earth tide
noise. A "compartment weighing many tons" is strongly coupled to the earth. The opposite approach is to uncouple from the earth as
much as possible. Your earthquake enviornment in the Pacific northwest is similar to here in Alaska. Your precision pendulum clock
is good enough to respond to monthly/daily earth tides. There is a 'catch 22' in trying to protect a pendulum clock. The pendulum
depends on constant acceleration of gravity. It ain't constant. If g varies or is noisy by one part in N then that sets the point of diminishing
return in your protection efforts.
Bill
/tvb
On 9/8/2021 7:36 PM, Bill Beam wrote:
Tom,
How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks. They are disturbed every couple of months
by earth quakes. By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks. Often the clocks will
signal an earth quake that is not felt.
Good luck.
Bill Beam
NL7F
Bill Beam
NL7F
Message: 14
Date: Thu, 9 Sep 2021 15:17:22 -0700
From: "Lux, Jim" jim@luxfamily.com
Subject: [time-nuts] Re: in-ground clock room
To: time-nuts@lists.febo.com
Message-ID: dbb895a4-371c-81bb-2ae0-7a982274642d@luxfamily.com
Content-Type: text/plain; charset=utf-8; format=flowed
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.
A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).
For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).
I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.
The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.
Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.
Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.
Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week
https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000
One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)
One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.
The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.
In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).Thanks,
/tvb
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Message: 15
Date: Thu, 9 Sep 2021 18:03:08 -0500
From: "Graham / KE9H" ke9h.graham@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CAPyJ-YWhz_C7r=meJ91skKMeQtBA7rRXVKZAtByCA3cARqo_Qw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
Sounds like we need a volunteer time-nut with motion picture camera
capability to document this event.
--- Graham
On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim jim@luxfamily.com wrote:
On 9/8/21 6:54 PM, Tom Van Baak wrote:
I am considering a below ground "clock room" away from the house. This
will be for some low-drift quartz oscillators and also a couple of
precision pendulum clocks. The goal is long-term, unattended, and very
undisturbed operation.For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural
isolation and temperature regulation. A couple tons of concrete gives
high stability vertical walls for the pendulum clocks.If any of you have personal or professional experience with the design
or construction of this sort of thing, especially experience with
precast (utility) vaults or poured concrete, please let me know.A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done. If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors. The big driver for most
people in a "residential" environment would be access. It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street. We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it. Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.Google "precast concrete manhole" and select accordingly.
You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own. And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/weekhttps://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.In case this gets too off-topic for time-nuts, off-list email to me is
fine (tvb@leapsecond.com).Thanks,
/tvb
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Message: 16
Date: Thu, 9 Sep 2021 20:47:29 -0400
From: Ben Bradley ben.pi.bradley@gmail.com
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Message-ID:
CA+wjhVsKT67AOghjXT91LwupF0FG3v=XiQEX4q0-2jVRQYHXnw@mail.gmail.com
Content-Type: text/plain; charset="UTF-8"
I've seen discussion of making a seismic vault (though not sure if
they used that name, making it harder to find in the haystack of
posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if
this is helpful:
https://url.emailprotection.link/?bj4D6X82wPC9xeltcsFCTXzK_O0xDS6ilwrNrr973O-CWyDkiYmR6AtIlije3Uhl-EhDjaWB722xAQMGo5pYzKsypwE_cPrdr7cPkFE8GrFQ48neYZCy5Hu7yuZjpSqlB
For possible immunity from earthquakes, LIGO uses some quite complex
control and feedback systems to hang its mirrors so that mild
earthquakes and local noise won't affect them. From what I've seen
over the years a lot of this info has been published, but I imagine it
would be quite expensive to reproduce. Maybe some sort of Ligo Lite
system would be feasible.
On Thu, Sep 9, 2021 at 10:13 AM Brent brent.evers@gmail.com wrote:
Seismic vaults are built similar to your requirements. I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing. Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).I've been in various seismic vaults and they can vary from very extravagant
to downright crude.On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood. Part of this is the
geology,
part is how the builder graded things to put in the subdivision.While that sounds ideal, the shale is tilted due to some thing running
into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.Yes, it’s all about some very local aspects of your geology. With some
care, I could move a few miles in one direction or another and be in a
very
different situation. (again thanks to just how this ran into that ….).Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...Bob
On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Tom Van Baak writes:
For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
that's vastly smaller than digging a basement, but much larger than
drilling a 8 inch round pipe. Digging down gives some natural isolation
and temperature regulation. A couple tons of concrete gives high
stability vertical walls for the pendulum clocks.I researched this extensively before we built a house 5 years ago.
Look at the plot on page 37 in this paper:
It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.In the end I concluded that I could do better in the comfort of my lab.
You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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Gilles Clement writes:
Magnetic levitation, dampening external vibrations ?
By theselves magnetic fields are just really good springs.
To get any kind of dampening you either need to add a
dash-pot (=shock-absorber) as a dissipative device or
you need to modulate the magnitic field to emulate
the same result.
I'm told the latter is much harder than it sounds.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Doesn't that depend on the configuration of the fields ?
For instance, a pair of facing like poles will repel and, as you say, make
a good spring.
But a magnet falling down an aluminium tube will go slowly, because of the
generated eddy currents and their subsequent fading due to the lossy
aluminium.
On Sat, Sep 11, 2021 at 2:02 PM Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Gilles Clement writes:
Magnetic levitation, dampening external vibrations ?
By theselves magnetic fields are just really good springs.
To get any kind of dampening you either need to add a
dash-pot (=shock-absorber) as a dissipative device or
you need to modulate the magnitic field to emulate
the same result.
I'm told the latter is much harder than it sounds.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
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Which suggests a possible damping mechanism.
From Tom Holmes, N8ZM
On Sep 11, 2021, at 10:08 AM, Adrian Godwin artgodwin@gmail.com wrote:
Doesn't that depend on the configuration of the fields ?
For instance, a pair of facing like poles will repel and, as you say, make
a good spring.
But a magnet falling down an aluminium tube will go slowly, because of the
generated eddy currents and their subsequent fading due to the lossy
aluminium.
Magnetic levitation, dampening external vibrations ?
By theselves magnetic fields are just really good springs.
To get any kind of dampening you either need to add a
dash-pot (=shock-absorber) as a dissipative device or
you need to modulate the magnitic field to emulate
the same result.
I'm told the latter is much harder than it sounds.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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It may be that the time constant of eddy current damping would be too
limited by the
inavailability of sufficiently good conductors (ar room temp, anyway). To
get really
long time constants one basically needs superconductivity somewhere in the
system.
Dana
On Sat, Sep 11, 2021 at 11:54 PM Tom Holmes tholmes@woh.rr.com wrote:
Which suggests a possible damping mechanism.
From Tom Holmes, N8ZM
On Sep 11, 2021, at 10:08 AM, Adrian Godwin artgodwin@gmail.com wrote:
Doesn't that depend on the configuration of the fields ?
For instance, a pair of facing like poles will repel and, as you say,
make
a good spring.
But a magnet falling down an aluminium tube will go slowly, because of
the
generated eddy currents and their subsequent fading due to the lossy
aluminium.
Magnetic levitation, dampening external vibrations ?
By theselves magnetic fields are just really good springs.
To get any kind of dampening you either need to add a
dash-pot (=shock-absorber) as a dissipative device or
you need to modulate the magnitic field to emulate
the same result.
I'm told the latter is much harder than it sounds.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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