Booleans with Sweep Parts

philip_jarrett

Hello!

I am struggling with a project in which I have a complex, sweeped shape that was extruded along a splined path from a splined profile. The issue is that I am unable to perform any boolean operations on this part. For example, when attempting to subtract a cylinder from the sweeped part for a bolt, Onshape is unable to solve. However, when I attempted to create an example scenario for this post, I was able to successfully subtract a cylinder from a spline profile that was sweeped along a non-spline half-circle. Any ideas what might be going on?

Thanks,
Philip

owen_sparks

Hi and welcome.  It's always easier to help if you supply a link to your file.

Details here on adice on asking for help, erm, if that helps:-

https://forum.onshape.com/discussion/9107/forum-post-checklist 

Cheers, Owen S.

philip_jarrett

Owen_Sparks,

I wanted to share but I'm technically fiddling with a teacher's CAD part and don't know if I have their permission to share publicly. However, I believe I found at least a clue as to what was going on.

I had a spline profile sweeping along a spline path. I applied a variable fillet to an edge of the resultant part. The slot I was attempting to subtract from the principal part was passing through the variably filleted area. When I suppressed fillets, Onshape was able to solve the boolean. Then, I was able to apply a new fillet. I wonder if the variable fillet presents a challenge for this scenario.

Thanks,
Philip

Jake_Rosenfeld

@philip_jarrett

It's likely that your subtraction was creating some kind on non-manifold geometry.  Here is an example:



This sort of subtraction created an infinitely-thin portion of geometry on the part, as well as an infinitely-small connection on the top and bottom faces.  This type of non-manifold geometry cannot be constructed in Onshape.