topic Re: Can't get circular shapes to constrain. in Fusion Support Forum

Can't get circular shapes to constrain.

wilburg — Tue, 21 Jan 2020 02:18:42 GMT

I build a sketch and have no difficulty getting lines and non-curvilinear shapes to become constrained. However when I add curved shapes (arc, circles) to the sketch, even if they are attached to fully constrained geometry in the sketch, I cannot get them to become constrained. Any idea?

Re: Can't get circular shapes to constrain.

wmhazzard — Tue, 21 Jan 2020 03:41:17 GMT

Please post an f3d file that shows your problem. If you add dimensions to the constraints you should not have a problem, unless you are dealing with one of the many bugs in the sketch environment. See that my sketch is fully constrained.

Re: Can't get circular shapes to constrain.

TheCADWhisperer — Tue, 21 Jan 2020 13:14:36 GMT

File>Export and then Attach your *.f3d file here that exhibits this behavior.

Re: Can't get circular shapes to constrain.

wilburg — Sun, 26 Jan 2020 16:03:42 GMT

I have found a solution

Re: Can't get circular shapes to constrain.

wilburg — Sun, 02 Feb 2020 14:10:46 GMT

I'm still having trouble getting arcs, and fit point splines to constrain. In the attached f3d file, I have a sketch which was fully constrained. I then attempt to join two line endpoints (both lines fully constrained) with either a series of arcs, or a fit post spline, and the resulting curved segment refuses to become constrained. I have tried everything I can think of, but no go.

Have you any ideas?

Re: Can't get circular shapes to constrain.

TheCADWhisperer — Sun, 02 Feb 2020 17:42:36 GMT

https://autode.sk/37XD8Ju

Re: Can't get circular shapes to constrain.

jeff_strater — Sun, 02 Feb 2020 17:49:37 GMT

Nice video, @TheCADWhisperer . Thanks for sharing that.

Fully constraining fit point splines is tricky, and some would argue, might not be worth doing at all. To fully constrain even a simple fit point spline, you have to:

fully dimension or constrain every single fit point
fully constrain any "active" tangent or curvature handles

You can do it, but it is often not worth the effort.

Re: Can't get circular shapes to constrain.

wilburg — Sun, 02 Feb 2020 20:39:59 GMT

Hi,

I appreciate your video, and it helped me understand how to simplify my sketch and make progress toward fully constraining it.

It ended, however, before actually showing me how I might constrain the fit point spline.

I’ve tried replacing the spline with multiple tangent arcs, and can’t seem to get those curves constrained.

If you have additional ideas, I would be thankful for anything you might be able to provide.

Thanks,

Wilbur

Re: Can't get circular shapes to constrain.

TheCADWhisperer — Sun, 02 Feb 2020 20:52:50 GMT

@wilburg wrote:
I’ve tried replacing the spline with multiple tangent arcs, and can’t seem to get those curves constrained.

If you have additional ideas, I would be thankful for anything you might be able to provide.

Attach the latest version here.

Re: Can't get circular shapes to constrain.

wilburg — Fri, 07 Feb 2020 15:00:00 GMT

I am attaching my most recent version of the offending file. Everything in the sketch named "side sketch" is fully constrained except for three three point arcs, and I can't seem to get these to cooperate regardless of what I have done.

I would have suspected that when creating geometry which is connected to already constrained stuff, the new additions would be constrained as well. The only thing I could think to do is to lock in the radii of the arcs - that didn't work.

Anything you can do to help me understand would be fully appreciated

Re: Can't get circular shapes to constrain.

TheCADWhisperer — Fri, 07 Feb 2020 15:12:31 GMT

Missing an arc radius dimension and arc location (centerpoint) dimensions.