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simple sketch not able to be constrained (by tsk)
Hi there,

I'm playing around with solvespace by trying to constrain a simple sketch I found in a paper about constraint solvers.
I can draw the sketch and set some constraints, but I cannot add missing constraints without getting the "SOLVE FAILED!unsolvable constraints" message.
E.g. try to add perpendicular constraintes at the two straight line corners...

Even in the not fully constrained sketch I cannot move lines or some points.

Is there a problem with the sketch or do I hit the edge of solvespace's capabilities?

Attached the sketch.

Mon Jun 10 2024, 08:18:18, download attachment OpenCSM.slvs
(no subject) (by Daniel Engineering Solutions)
I took a look at your sketch and a couple things jumped out at me right off the bat. First, the scale of the thing is massive, which may be part of the issue. One way to work around this is to model the item at a smaller scale (it says the bottom line is over 1500 inches) and then import the sketch into another solvespace file where you scale it up to the proper size.

Another item I noticed was that the model isn't started from the origin. If that was done on purpose, then you may have hit the limits of the solver. I have found that keeping things as defined as possible (especially at large scale) helps modeling to go smoothly.
Mon Jun 10 2024, 14:28:18
(no subject) (by ruevs)
Can you post a link to the paper?
Tue Jun 11 2024, 01:12:40
(no subject) (by ruevs)
Otherwise yes - the line at the bottom of your sketch is 38294.6085178064mm long. The solver has known problems with big objects:

Attached is a version where the length of the bottom line is 382.946085178mm and has no problems with constraints.

I made it with `CTRL-A`, `CTRL-C`, `CTRL-A`, Del, `CTRL-T` (Edit | Paste transformed...) with a `scale` of 0.01.

I'm still curious about the article and what the sketch was intended to look like when fully constrained.
Tue Jun 11 2024, 12:22:48, download attachment OpenCSM_Small.slvs
(no subject) (by ruevs)
Tue Jun 11 2024, 12:29:23
(no subject) (by ruevs)
As a result of finding the article attached is a fully constrained according to "Figure 2" and "Table 2" sketch.

It required a few construction lines.
Tue Jun 11 2024, 12:44:52, download attachment OpenCSM_SmallFullyConstrainedZeroDOF.slvs
(no subject) (by ruevs)
OpenCSM an interesting vapourware
or at least I do not see the "open" source.
Tue Jun 11 2024, 15:33:59
(no subject) (by ruevs)
Tue Jun 11 2024, 15:45:24
(no subject) (by ruevs)
Tue Jun 11 2024, 15:47:31
Re: simple sketch not able to be constrained (by tsk)
Hi ruevs,

Sorry for not answering earlier, I wasn't online.
Yes, that was the paper.
Thanks for your help.
Are you working on solvespace?

Wed Jun 12 2024, 04:15:59
Re: simple sketch not able to be constrained (by tsk)

Just for the records:
This is the exact sketch like in the paper.
I needed three construction lines to accomplish that.
Would it be possible to add constraints that would allow to constrain the sketch without these construction lines?
Wed Jun 12 2024, 05:33:23, download attachment OpenCSM.slvs
(no subject) (by ruevs)
> Are you working on solvespace?

A little bit :-) I do have commit privilege.

> Would it be possible to add constraints that would allow to constrain the sketch without these construction lines?

One construction line from your solution can be avoided - the one where the two arcs on the right are tangent. Just make the "radius" one go through the center of the bottom ark - see my solution above.

The other two construction lines are (currently) unavoidable.

It is possible to create a new type of constraint - "angle between line and arc" or "angle between line and curve" but since it is easily achieved with a tangent construction line it is probably not worth it.
Mon Jun 17 2024, 11:03:41
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