Bending a pipe ...
I've been using OpenScad for quite a while and find it fits with the way
my mind works in a way that many CAD tools don't.
But I have a need to generate a bend in a pipe and I'm having difficulty
putting it down in scad and I'm hoping for some
help.
In essence I need to generate a pipe that is 30mm in diameter with a
wall thickness of (say) 3mm with a bend of 120 degrees.
It could ether be a smooth bend or a sharp bend - although the latter
would be more useful due to space constraints.
I can sort of see how I might generate a cylinder and diff it with a
cube at an angle, but I cannot see how to join two such
cylinders to form a watertight solid without a lot of fiddling - there
must be a better way.
Any clues, tips, examples very welcome,
Dave
Google found this:
https://www.thingiverse.com/thing:71464
On Sat, Jul 2, 2022 at 5:09 PM Dave softfoot@hotmail.com wrote:
I've been using OpenScad for quite a while and find it fits with the way
my mind works in a way that many CAD tools don't.
But I have a need to generate a bend in a pipe and I'm having difficulty
putting it down in scad and I'm hoping for some
help.
In essence I need to generate a pipe that is 30mm in diameter with a
wall thickness of (say) 3mm with a bend of 120 degrees.
It could ether be a smooth bend or a sharp bend - although the latter
would be more useful due to space constraints.
I can sort of see how I might generate a cylinder and diff it with a
cube at an angle, but I cannot see how to join two such
cylinders to form a watertight solid without a lot of fiddling - there
must be a better way.
Any clues, tips, examples very welcome,
Dave
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There's no way to take a piece of geometry - a cylinder, say - and bend
it. The kind of transformations that OpenSCAD can do simply cannot make
that kind of change. You must create the object in its bent form.
A general solution would probably involve one of the sweep functions,
e.g.
https://github.com/revarbat/BOSL2/wiki/skin.scad#functionmodule-path_sweep
. Somebody more familiar with those can supply an example.
But here's a first-principles solution for straightforward bends in pipes:
module pipe_bend(angle, bend_r, id, od) {
rotate_extrude(angle=120) {
translate([bend_r,0,0]) {
difference() {
circle(d=od);
circle(d=id);
}
}
}
}
pipe_bend(angle=120, bend_r=30, id=24, od=30);
You would then need to mate straight pipes onto the ends as required.
(A sweep-based solution would do that for you, since you would sweep
through the entire length of the pipe, straight and bent segments alike.)
You can use rotate_extrude maybe, if you can use a circular bend. If
you want something fancier, I recommend BOSL2's path_sweep function,
which can generate a cylindrical extrusion that follows any 3d path.
https://github.com/revarbat/BOSL2/wiki/skin.scad#functionmodule-path_sweep
include<BOSL2/std.scad>
shape = difference([circle(r=10),circle(r=7)]);
path = [for(t=[0:3:180]) [t, 120*sin(t)]];
path_sweep(shape, path);
On Sat, Jul 2, 2022 at 6:09 PM Dave softfoot@hotmail.com wrote:
I've been using OpenScad for quite a while and find it fits with the way
my mind works in a way that many CAD tools don't.
But I have a need to generate a bend in a pipe and I'm having difficulty
putting it down in scad and I'm hoping for some
help.
In essence I need to generate a pipe that is 30mm in diameter with a
wall thickness of (say) 3mm with a bend of 120 degrees.
It could ether be a smooth bend or a sharp bend - although the latter
would be more useful due to space constraints.
I can sort of see how I might generate a cylinder and diff it with a
cube at an angle, but I cannot see how to join two such
cylinders to form a watertight solid without a lot of fiddling - there
must be a better way.
Any clues, tips, examples very welcome,
Dave
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
Adrian Mariano wrote:
You can use rotate_extrude maybe, if you can use a circular bend. If
you want something fancier, I recommend BOSL2's path_sweep function,
which can generate a cylindrical extrusion that follows any 3d path.
https://github.com/revarbat/BOSL2/wiki/skin.scad#functionmodule-path_sweep
include<BOSL2/std.scad>
And Example 13 is a toothed belt - something I have been looking for!
But if I copy and paste the code, nothing happens. Evidently I need to download BOSL2/std.scad but where do I find it and when i have got it, where do Iput it? (No rude answers please).
Also, the wiggly belt looks very complicated, but is mathematically probably relatively simple. What I need is a simple belt that is probably mathematically very complicated - an oval with straight sides as found in practice.
And then it needs to be animated … (sigh)
Any ideas, anyone?
BOSL2 is a large library with many files. You can download it at
https://github.com/revarbat/BOSL2 by clicking the green button that
says CODE and downloading the zip file. The README.md file gives
some instructions on where to put the files.
Note that what is complicated about example 13 mathematically is
making the belt twist. Making an untwisted belt would be much easier.
I don't understand your description of the belt you need to make.
Animating the belt should be pretty easy if you plan your code so you
can render the belt in any position.
On Wed, Jul 6, 2022 at 7:03 PM mikeonenine@web.de wrote:
Adrian Mariano wrote:
You can use rotate_extrude maybe, if you can use a circular bend. If you want something fancier, I recommend BOSL2's path_sweep function, which can generate a cylindrical extrusion that follows any 3d path.
https://github.com/revarbat/BOSL2/wiki/skin.scad#functionmodule-path_sweep
include<BOSL2/std.scad>
And Example 13 is a toothed belt - something I have been looking for!
But if I copy and paste the code, nothing happens. Evidently I need to download BOSL2/std.scad but where do I find it and when i have got it, where do Iput it? (No rude answers please).
Also, the wiggly belt looks very complicated, but is mathematically probably relatively simple. What I need is a simple belt that is probably mathematically very complicated - an oval with straight sides as found in practice.
And then it needs to be animated … (sigh)
Any ideas, anyone?
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
Thanks for the info. I should have found that myself, but from past experience one can end up ploughing through endless stuff and still not find what one wants, so I thought I would ask.
Meanwhile, progress - of sorts:
At least i now get a big red spot next to the line include <BOSL2 ...
I did rename BOSL2-Master to just BOSL2 as per the instructions.
I have restarted my laptop.
What’s missing?
I would be happy with a toothed belt going round two cogged wheels to start with - the basic application in the real world. From there I want to see if it is possible to get the belt crossed and twisted in the middle to drive the wheels in opposite directions.
Did you put the BOSL2 directory in the location specified in the
README for your operating system? Rebooting isn't necessary. If in
OpenSCAD you go to File->Show library folder you should see the BOSL2
folder in there.
On Sat, Jul 9, 2022 at 9:38 PM mikeonenine@web.de wrote:
Thanks for the info. I should have found that myself, but from past experience one can end up ploughing through endless stuff and still not find what one wants, so I thought I would ask.
Meanwhile, progress - of sorts:
At least i now get a big red spot next to the line include <BOSL2 ...
I did rename BOSL2-Master to just BOSL2 as per the instructions.
I have restarted my laptop.
What’s missing?
I would be happy with a toothed belt going round two cogged wheels to start with - the basic application in the real world. From there I want to see if it is possible to get the belt crossed and twisted in the middle to drive the wheels in opposite directions.
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org
Had great fun doing this a while ago, but it’s only an optical illusion: the true motion is that of the little black spot on the right hand wheel. So it’s no use in conjunction with other parts doing regular $t*360 motion.
This appears to be a syntax error after the include statement.
It appears that you have not surrounded the body of the tree module with {}
For example:
module tree(l=1500,sc=0.7,depth=10)
{
recolor...
cylinder...
...
}
On Sat, Jul 9, 2022 at 8:39 PM mikeonenine@web.de wrote:
Thanks for the info. I should have found that myself, but from past
experience one can end up ploughing through endless stuff and still not
find what one wants, so I thought I would ask.
Meanwhile, progress - of sorts:
At least i now get a big red spot next to the line include <BOSL2 ...
I did rename BOSL2-Master to just BOSL2 as per the instructions.
I have restarted my laptop.
What’s missing?
I would be happy with a toothed belt going round two cogged wheels to
start with - the basic application in the real world. From there I want to
see if it is possible to get the belt crossed and twisted in the middle to
drive the wheels in opposite directions.
OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org