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Vertex on revolve axis
vidyut_vivekkumar
Member Posts: 2 ✭
Hi Onshape community,
My project has a sketch with a point on the axis I'm trying to revolve around, but the revolve feature says it's self intersecting. I don't see anything self intersecting when I check the sketch.
https://cad.onshape.com/documents/a398f96ab77e7c2712b2088c/w/96b1384b7b0609deda5c3695/e/a8d9d3102e601e013ad41a0b
The model in question ^^^
0
Answers
did you make it public? I couldn't get in
Hi,
Also beginner here. I am experiencing the same problem and it seems to be a bug. When point is on revolving axis full revolve cannot be created. I move point outside revolving axis just tiny bit and is OK.
Seems like this should work. I retraced the sketch image. Fully defined sketch with upper right vertex coincident with revolve axis. Full revolve fails. Revolve of 359.9 degrees is successful. - Scotty
This shouldn't need to work. Why are you trying to create infinitely thin geometry? What's your overall goal?
Something infinitely thin is not possible to manufacture.
What resulted in the revolve is a solid with a very small wedge gap in it. Thus, I don't understand the reference to 'create infinitely thin geometry'. - Scotty
Document (part studio 2)
If the vertex is right on the revolve line, the revolve would be infinitely thin at that point. This is called "nonmanifold geometry", and our geometry kernel disallows that.
A full revolve would create two faces which touch in their centres, where there is no edge.
In real life if you tried to do this you would break through the material.
By doing an incomplete revolve you are creating edges at that point, which necessarily has to be allowed. The two cases are topologically very different
Thanks for responding. So, intersecting a point with the axis results in no thickness i.e. no geometry at that point?
. - Scotty
Bingo. That point results in non-manifold geometry, which the Parasolid kernel can't handle. There's a vertex which is both inside and outside at the same time, which isn't allowed.
Although technically not self intersecting. It's kind like asking a computer or calculator to divide by zero. Error
Good analogy. Thanks All. - Scotty
Also called a knife-edge. Something most CAD doesn't handle well.
Got it. Thanks for all answers.