Re: Gear Making for a Toy Car
Rogier, why would you need to buy British screws to repair something made
in the USA? The BSW screw type is not used in the USA. I mean, maybe
there's legacy stuff floating around where it was used? But mcmaster.com,
my online hardware supplier, has tons of UNC threaded screws (many
thousands) and lots of metric screws (also thousands) and not a single BSW
screw.
On Wed, Feb 8, 2023 at 4:25 AM Rogier Wolff R.E.Wolff@bitwizard.nl wrote:
On Tue, Feb 07, 2023 at 06:43:27PM -0500, Adrian Mariano wrote:
You sure about that? Let's see...when I search for 1/2-12 screws I get
this:
So why are they selling it if nobody uses it?
Maybe because out here we occasionally need to repair stuff made in
the USA? I'm guessing that there are specialized machine-screw shops
in the USA that also carry M3, M4 ...
Or when you get something that uses a metric screw that needs
replacing, you just toss the whole thing?
Still, in GB I'd think you're more likely to find people using
non-metric screws than say in Germany.
Roger.
--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110
**
** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 **
f equals m times a. When your f is steady, and your m is going down
your a is going up. -- Chris Hadfield about flying up the space shuttle.
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On Wed, Feb 08, 2023 at 09:10:22AM -0500, Adrian Mariano wrote:
Rogier, why would you need to buy British screws to repair something
made in the USA? The BSW screw type is not used in the USA.
Someone found a shop selling one of the three variants and claimed:
They must still use those overthere. I was trying to argue: the fact
that they sell a variant doesn't mean that it's widely used. It might
be just for "maintenance and repair" for older stuff.
Now I agree with you. I own lots of metric stuff. That's what I use. I
own a few UNC screws. e.g. "camera fastners" are 1/4 UNC course if I
understand things correctly. (and the screws used to connect DB25
serial port connectors are also UNC-something. I have a project where
those are necessary, so I bougth a few.) But I too hadn't heard of BSW
and I don't know that I own any.
Roger.
--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 **
** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 **
f equals m times a. When your f is steady, and your m is going down
your a is going up. -- Chris Hadfield about flying up the space shuttle.
On 2/8/2023 1:20 AM, nop head wrote:
Plumbing pipe sizes and fasteners are still still imperial in the UK
though. Probably due to the compatibility requirements.
If British pipe sizes are anything like US pipe sizes, the nominal size
doesn't have anything to do with the measurements, so you could just
give the existing sizes new metric numbers that are sort of close.
A US Nominal Pipe Size of 1" has an OD of 1.315" and an ID of anywhere
from 0.957" to 1.185".
Just call it 25mm (converting the NPS) or 33mm (converting the OD),
while preserving the required oddball size.
And in fact they've already done that - ISO 6708 defines a "DN" number
that is very loosely a conversion of the NPS to millimeters.
On 2/8/2023 1:24 AM, Rogier Wolff wrote:
I'm guessing that there are specialized machine-screw shops in the USA
that also carry M3, M4 ...
Yep. We call them "hardware stores" :-)
I'm pretty sure that my neighborhood hardware store has a complete
selection of metric fasteners.
Surprisingly, Lowe's (a national chain) doesn't stock the smaller metric
sizes. But my local Ace does.,
On Wed, Feb 8, 2023 at 4:59 PM Jordan Brown openscad@jordan.maileater.net
wrote:
On 2/8/2023 1:24 AM, Rogier Wolff wrote:
I'm guessing that there are specialized machine-screw shops in the USA
that also carry M3, M4 ...
Yep. We call them "hardware stores" :-)
I'm pretty sure that my neighborhood hardware store has a complete
selection of metric fasteners.
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My local home center does have some metric screws. A complete selection?
Of course not. And the prices are insane. Like a bag of 3 screws is $1.25
or a bag of two screws for $2.75. But it's not better if you are looking
for Imperial screws. That's why I just buy all my screws online.
On Wed, Feb 8, 2023 at 5:58 PM Jordan Brown openscad@jordan.maileater.net
wrote:
On 2/8/2023 1:24 AM, Rogier Wolff wrote:
I'm guessing that there are specialized machine-screw shops in the USA
that also carry M3, M4 ...
Yep. We call them "hardware stores" :-)
I'm pretty sure that my neighborhood hardware store has a complete
selection of metric fasteners.
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Not entirely. The MGI Zip Navigator golf trolley has at least some non-metric metric parts. They’re odd even for SAE/UK.
-Bob
Tucson AZ
On Feb 7, 2023, at 15:40, Andy Cole 1943ajlc@gmail.com wrote:
We're all metric in Oz, mate
Andy
On Wed, 8 Feb 2023, 6:01 am Bob Carlson, <bob@rjcarlson.com mailto:bob@rjcarlson.com> wrote:
Thanks. I’m confused by your use of “walls”, 5 walls, 3-4 walls, etc. Can you elucidate?
Are these square threads on the clamps? Just curious. I suspect they are harder to print than 60 degree threads.
BTW, I verified that the bolt I need is 1/2-12, an odd size, but apparently used occasionally, esp in the UK and Australia I guess.
-Bob
Tucson AZ
On Feb 7, 2023, at 03:24, Roger Whiteley via Discuss <discuss@lists.openscad.org mailto:discuss@lists.openscad.org> wrote:
From: Roger Whiteley <roger.whiteley@me.com mailto:roger.whiteley@me.com>
Subject: [OpenSCAD] Re: Gear Making for a Toy Car
Date: February 7, 2023 at 03:24:49 MST
To: discuss@lists.openscad.org mailto:discuss@lists.openscad.org
Reply-To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org mailto:discuss@lists.openscad.org>
@Bob Carlson.
I print screw threads vertically - several components I make for our machines have printed screws:
A clamp - all in PLA - the clamp part took a lot of (re)-designing to prevent bending [and snapping] under load.
I print this screw with the following settings - this screw is 16mm in diameter with a pitch of about 4mm:
0.16mm layer height, 5 walls [2mm], Z seam random, infill 30% gyroid.
The second one is a pinch clamp, again vertically printed in PLA, but its only 10mm in diameter, with a 2mm pitch, 3 walls at the same layer height and infill.
Being so 'thin' it is prone to snapping at the thread root, so for the length of the screw thread I embed an empty 'cylinder', creating a void in the centre, the slicer sees this as a wall, so it gets the same processing applied - a 1.2mm walled hollow section, being cylindrical it has no stress raising corners and problem solved. Its invisible and nobody is any the wiser - I think I saw Angus on Maker's Muse You Tube channel doing something similar, so I'm not claiming originality.
BTW random Z means there is no continuous seam up the thread in one place [but you knew that already :-)].
Printing gears is 'interesting', the change gears on a mini lathe are mostly injection moulded so have no directional alignment in the material, 3d printing straight gears results in much stronger gears owing to the wall alignment - but the weakest link is always supposed to be the woodruff key for a metal gear train in the event of a jam, not the teeth :-).
Bevel gears are trickier, I print them on their back if they are large, or teeth down with a spacing ring to lift them off the print surface - we've had more issues with teeth shearing on bevel gears owing to the orientation - 3 to 4 walls, for a 4 inch bevel with 30 teeth we use 15% gyroid - from our experience gyroid infill works.
Examples from the past: Myford lathes had 20dp machined cast iron gears with woodruff keys, but a 1974 Volvo 144 had a cam drive gear machined from tufnol + woodruff key, quiet, but it did strip eventually.
HTH Roger.
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Well, I just bought this golf trolley from MGI, an OZ company. The design is not more than 2-3 years old max. I’m in the USA but I try to work exclusively in metric. It really irritates me when I buy a product and it contains imperial/SAE unit stuff and I have to work with it. And at the hardware store I have to deal with the irritation of the helpers who get kind of annoyed when I ask about metric stuff.
I am curious why a company would use the odd size 1/2-12. It is a bolt for attaching things and I suspect they want to make it as hard as possible to DIY your own attachments, which of course is what I am doing.
britishfasteners.com http://biritchfasteners.com/ was the only source I found.
-Bob
Tucson AZ
On Feb 8, 2023, at 02:20, nop head nop.head@gmail.com wrote:
Yes we can buy old imperial fasteners for legacy applications. For example a friend has a 200 year old house and needed to mend a door knob that used a Whitworth thread but I don't think anything new is designed with them.
Plumbing pipe sizes and fasteners are still still imperial in the UK though. Probably due to the compatibility requirements.
On Tue, 7 Feb 2023 at 23:44, Adrian Mariano <avm4@cornell.edu mailto:avm4@cornell.edu> wrote:
You sure about that? Let's see...when I search for 1/2-12 screws I get this:
https://britishfasteners.com/bsw-1-2-12-x-1-1-2-stainless-hex-screw-7793.html
And what is BSW?
British Standard Whitworth (BSW) is an imperial-unit https://en.wikipedia.org/wiki/Imperial-unit-based screw thread https://en.wikipedia.org/wiki/Screw_thread standard, devised and specified by Joseph Whitworth https://en.wikipedia.org/wiki/Joseph_Whitworth in 1841 and later adopted as a British Standard https://en.wikipedia.org/wiki/British_Standard. It was the world's first national screw thread standard, and is the basis for many other standards, such as BSF https://en.wikipedia.org/wiki/British_Standard_Fine, BSP https://en.wikipedia.org/wiki/British_Standard_Pipe, BSCon https://en.wikipedia.org/w/index.php?title=British_Standard_Conduit&action=edit&redlink=1, and BSCopper https://en.wikipedia.org/w/index.php?title=British_Standard_Copper&action=edit&redlink=1.
So why are they selling it if nobody uses it? Interesting to note that BSW has a 55 deg thread pitch instead of 60 deg thread pitch, so the screws will not mate with US standard hardware even in cases where the dimensions and pitch are the same. Looks like British Standard Pipe is also based on imperial units, and looks like they are still in use and listed in ISO standard documents.
On Tue, Feb 7, 2023 at 6:16 PM nop head <nop.head@gmail.com mailto:nop.head@gmail.com> wrote:
And in the UK. It is just the US that use the old units.
On Tue, 7 Feb 2023 at 22:41, Andy Cole <1943ajlc@gmail.com mailto:1943ajlc@gmail.com> wrote:
We're all metric in Oz, mate
Andy
On Wed, 8 Feb 2023, 6:01 am Bob Carlson, <bob@rjcarlson.com mailto:bob@rjcarlson.com> wrote:
Thanks. I’m confused by your use of “walls”, 5 walls, 3-4 walls, etc. Can you elucidate?
Are these square threads on the clamps? Just curious. I suspect they are harder to print than 60 degree threads.
BTW, I verified that the bolt I need is 1/2-12, an odd size, but apparently used occasionally, esp in the UK and Australia I guess.
-Bob
Tucson AZ
On Feb 7, 2023, at 03:24, Roger Whiteley via Discuss <discuss@lists.openscad.org mailto:discuss@lists.openscad.org> wrote:
From: Roger Whiteley <roger.whiteley@me.com mailto:roger.whiteley@me.com>
Subject: [OpenSCAD] Re: Gear Making for a Toy Car
Date: February 7, 2023 at 03:24:49 MST
To: discuss@lists.openscad.org mailto:discuss@lists.openscad.org
Reply-To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org mailto:discuss@lists.openscad.org>
@Bob Carlson.
I print screw threads vertically - several components I make for our machines have printed screws:
A clamp - all in PLA - the clamp part took a lot of (re)-designing to prevent bending [and snapping] under load.
I print this screw with the following settings - this screw is 16mm in diameter with a pitch of about 4mm:
0.16mm layer height, 5 walls [2mm], Z seam random, infill 30% gyroid.
The second one is a pinch clamp, again vertically printed in PLA, but its only 10mm in diameter, with a 2mm pitch, 3 walls at the same layer height and infill.
Being so 'thin' it is prone to snapping at the thread root, so for the length of the screw thread I embed an empty 'cylinder', creating a void in the centre, the slicer sees this as a wall, so it gets the same processing applied - a 1.2mm walled hollow section, being cylindrical it has no stress raising corners and problem solved. Its invisible and nobody is any the wiser - I think I saw Angus on Maker's Muse You Tube channel doing something similar, so I'm not claiming originality.
BTW random Z means there is no continuous seam up the thread in one place [but you knew that already :-)].
Printing gears is 'interesting', the change gears on a mini lathe are mostly injection moulded so have no directional alignment in the material, 3d printing straight gears results in much stronger gears owing to the wall alignment - but the weakest link is always supposed to be the woodruff key for a metal gear train in the event of a jam, not the teeth :-).
Bevel gears are trickier, I print them on their back if they are large, or teeth down with a spacing ring to lift them off the print surface - we've had more issues with teeth shearing on bevel gears owing to the orientation - 3 to 4 walls, for a 4 inch bevel with 30 teeth we use 15% gyroid - from our experience gyroid infill works.
Examples from the past: Myford lathes had 20dp machined cast iron gears with woodruff keys, but a 1974 Volvo 144 had a cam drive gear machined from tufnol + woodruff key, quiet, but it did strip eventually.
HTH Roger.
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