Trouble With STL Imports

harrison_beeg

I have imported this STL file into a new document. It imports as a "surface" and gives the error 'did not regenerate properly, imported part contained faults". I turned on "highlight boundary edges" and found 2 edges that I believe are causing the error. Because of the error, I am unable to modify the surface which is my goal.
Is there any way to fix the error so I can modify the part and put holes into it?

*I am unable to link the STL file so here is the website I downloaded it from: https://www.thingiverse.com/thing:5583268/files
The file name is "Base_Rev_2.1.stl"

Thank you for any help

glen_dewsbury

Making your document public and sharing a link here will let folks view for comment since the stl is already imported.

GWS50

STLs are notoriusly tricky, especially in the CAD environment.
There are 2 Non-manifold edges which come to a point and therefore make the mesh non-watertight so to fix this they need to be given some 'body' or thickened.
Unfortunately, Onshape, as brilliant as it is, can't fix this problem but you can get around it.

Take a look at this document.

https://cad.onshape.com/documents/6bfa65170c6a54794121f3db/w/501a8f436a1b34a7bed55700/e/185d809eb174df8ee761cd29

In the TAB - Base 2.1-Additions there is some construction geometry to rectify the errors. The two points at the tip of the triangles have been widened to create a better connection to the inner ring.
The problem surface and the new part were exported as separate parts and Boolean-ed in another program. Once re-imported the surface became a part.

See TAB - Base 2.11