Boolean with offset does not work on complicated fillet surfaces

dana_kelley262

In this document there are two Boolean. The first leaves out the two surfaces that cause a failure. The second only has the two surfaces that cause the failure.

The offset of 0.015" is being used. Without the offset it works.

Initially I selected 0.015" offset all given that is the desired result.

Why doesn't this work?

https://cad.onshape.com/documents/ea384be47743ca8e3972c8ac/w/6f324d270daf66d1b42e091a/e/5021f3be70cc6cfb37ecf583

NeilCooke

dana_kelley262 said:

Thanks for your feedback. Interesting solution. I've submitted a bug report to find out what the issue is before moving forward. 

Hi Dana, it is likely that the error is generated by Parasolid not being able to resolve the geometry into a manifold solid body (sorry for the jargon). This is something that is very geometry specific and would take time to fix only for this specific case. Subtracting the entire body with offset is computationally intensive. Perhaps subtracting with no offset, then using the Move Face command to apply the offset to the required faces may be a better solution.

The reason the fillet is "split" as in @steve_shubin 's image above, is that the original geometry (before the fillet) has four edges sharing a single vertex.

dana_kelley262

Never mind............. missed selecting the small wedged faces in the move face

steve_shubin

@dana_kelley262

I don’t know why the boolean with offset failed.


But if you’re interested in a workaround,
see the document below.


https://cad.onshape.com/documents/68bc73df32d1e5351be70c4f/w/16f68abd9376f30ca3cdfd84/e/d7696fbbd6d958faf1c8209c

dana_kelley262

Thanks for your feedback. Interesting solution. I've submitted a bug report to find out what the issue is before moving forward. 

steve_shubin

@dana_kelley262

I got it to work by using a single boolean — the way you wanted it to work

I used REPLACE FACE to eliminate the lines shown below. Then I was able to use a single boolean with offset on ALL THE FACES.

https://cad.onshape.com/documents/4ae02264d7f77c75f8239e4a/w/b96aafb51f9cc03b34ab1898/e/7e3aa785b65a1369e2142982

NeilCooke

dana_kelley262 said:

Thanks for your feedback. Interesting solution. I've submitted a bug report to find out what the issue is before moving forward. 

Hi Dana, it is likely that the error is generated by Parasolid not being able to resolve the geometry into a manifold solid body (sorry for the jargon). This is something that is very geometry specific and would take time to fix only for this specific case. Subtracting the entire body with offset is computationally intensive. Perhaps subtracting with no offset, then using the Move Face command to apply the offset to the required faces may be a better solution.

The reason the fillet is "split" as in @steve_shubin 's image above, is that the original geometry (before the fillet) has four edges sharing a single vertex.

dana_kelley262

I saw that the no offset worked but did not realize there was a second step that could be used to add the offset. So one would ask this question. Why not break it into two processes? No offset followed by adding the offset. A hack perhaps but it eliminates future head scratching and hides it from the users.

This solution worked just fine so Ill be moving on.

dana_kelley262

It did not quite work after all.

dana_kelley262

Never mind............. missed selecting the small wedged faces in the move face