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Cannot Boolean Subtract

gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
edited March 2021 in Using Onshape
I would like to know what is preventing this Subtract to work:

Not much more to say really :) Here is the project.


  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    edited March 2021
    I think the matter is this: the sketch to create the orange part above has splines that are defined as coincident. But as I zoom in, I notice they aren't really:

    (I've tried to cover the gap with a line, to no av)
  • tim_hess427tim_hess427 Member Posts: 648 ✭✭✭✭
    The issue is with the offset curve and the spline that bridges the gap in the "tyre base" sketch. The two curves overlap in two places, which created a little tiny gap when the shape revolved. This was interfering with the boolean. Adjust the spline highlighted in orange to make sure that it doesn't dip cross over the other lines and you should be fine.

  • John_P_DesiletsJohn_P_Desilets Onshape Employees, csevp Posts: 235
    @gauthier_östervall This sketch has a small section that is crossing over the other spline. This creates a closed profile. When the revolve is created, this small profile is not selected creating a void in the part. 

    Void in part from closed profile. 

    Adjust the sketch to remove the closed profile. 

    Good luck! 

  • John_P_DesiletsJohn_P_Desilets Onshape Employees, csevp Posts: 235
    @tim_hess427 beat me to it. 
  • gauthier_östervallgauthier_östervall Member Posts: 99 ✭✭
    @tim_hess427 @John_P_Desilets

    You are great! I was mistaken in thinking that the tangent constraint on the shorter spline should keep it out of the longer one. I can see why now.

    What I don't understand is why this would disturb the Boolean operation. There are two parts (the tyre has an unexpected hole, but ok, still a part). They intersect. Why shouldn't I be able to Subtract?

  • tim_hess427tim_hess427 Member Posts: 648 ✭✭✭✭
    At some point in there, there was probably some "non-manifold geometry" which is just saying there was some material with zero thickness somewhere so the software threw an error.
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