How to Remove a fillet on an imported part

robert_newland

Hello,

I have imported some parts from elsewhere but want to remove the fillet they've put in place on many of the edges.  Is there an easy/ 'best method' way to do this? 

eric_pesty

https://cad.onshape.com/help/Content/modifyfillet.htm?Highlight=MODIFY FILLET

S1mon

I forgot that Modify fillet had a remove option. Does this do anything different from just deleting a face with the heal option?

glen_dewsbury

Just tried @S1mon. The result seems to look the same.

Time result varies.
Modify fillet- 3ms/3ms
Delete face and heal- 7ms/11ms
Tried again with window select of both parts to see what happens.
One is imported and the other new. The new fillets on new part seems to be slowest. Hmmm

S1mon

Interesting. I did a little more investigation, and there are some differences with more complex fillet arrangements.

This is not at all exhaustive, but here's Modify fillet/Remove:

and here's the same thing with Delete face/Heal - which fails:


Here's a second comparison. Modify fillet/Remove:

and the same selection with Delete face/Heal:

If the "Delete fillet faces" check box is unchecked, this also fails:


This was all done with native Onshape CAD, but it's really interesting the difference in how the two features treat the same selections. Modify fillet/Remove seems to be better suited than remove face in terms of doing sensible things (assuming Onshape recognizes the fillets).

eric_pesty

I think the modify fillet tool automatically expands the selection to tangent connected faces with the same radius (and the performs a "delete face" in the background).
You could probably reproduce the behavior using the "create selection" tool and a delete face but might as well use the "correct" tool for the job!

glen_dewsbury

The RMB will let select all radii with the same radius as the one you're hovering over.
Buuuttt. If you want to delete all fillets to keep things simple a window select of all parts can be used when invoking modify fillet to change them all to same or eliminate all at once and will ignore the other selections in the window. That sounds like a time saver.

@robert_newland As you can see, there are many ways to skin a cat.

EvanReese

Digging into the actual code doesn't tell me that much here either since the Modify Fillet feature code just calls @opModifyFillet() which is where it goes behind the curtain to talk to Parasolid. It's not just an opDeleteFace(), but for all I know it's doing the same thing in Parasolid, plus some selection logic. 

robert_newland

Wow. Thanks all.  I assumed the modify fillet tool only worked on fillets you'd created yourself, but seems they do work on parts you've imported as well. 

Whilst I waited for the question to be approved I worked out a technique where I 'Boolean differenced' away the face and then re 'thickened' it. If that makes sense.
It was a little laborious and modify fillet is a lot quicker.