Boolean issues

Hi all,

This isn’t necessarily a Mac issues but more than likely an ex AutoCAD user issue :smile:

To keep it simple: I’ve revolved a profile through 360 degrees, I’m trying to subtract an extruded shape from both sides (but only a few mm deep on both sides not a through cut)

When I subtract the shape from the opposite side to where the start and finish of the profile i’ve revolved is there are no issues. The shape checks with no issues and when it’s meshed it’s a good mesh.

When I try to boolean the shape form the side where the revolved profile starts and ends the model still check OK but when I mesh it there are errors.

When I explode the model and look at the surface where the start and end is the bold line splits some of the details in two. Why is this?

Is there some way to make a seamless revolved shape?

i’ve even tried to split the cylinder in two and only cut from the two faces without the profile start and end but that just causes more problems when I join the two surfaces I have 2 profile edges with errors.

There are a lot of other operations on this model but this is where the error creeps in right at the beginning.

Thanks for reading, looking forward to hearing you thoughts.



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Hi Andy,

could you post your file or show us a picture of it before doing the boolean operation ?


You can see the highlighted section of the revolved surface. If I boolean a shape from that side of the model it splits the faces either side of that sectional detail.

If I boolean the same procedure on the opposite side there is no ‘seam’ so there are no errors…

Just wondered if there was a way to remove that start and end point of the revolved surface?

Here is a view of both side with the operation - you can see it has split some of the faces into two sections but on the opposite side the face isn’t split… This is due to the start and end point of the revolved surface.

If I boolean the word from the side without the start and end point of the revolved surface (as a solid model not a surface as you see in my screen shots) then mesh it, there are no issues, it’s a clean mesh and makes and STL with no errors.

When I do the same on the start / finish side of the revolved surface the mesh is full of errors.

i’ve even tried it with simple shapes, it’s not errors in the extruded text i’m boo leaning with. Both solid models check out OK and both mesh OK with no errors

Yes, use ExtractSrf to separate the revolved surface from the solid. Then use SrfSeam to relocate the seam to a location outside of the Boolean area. Join all surfaces back together into a solid and Boolean. The seam can’t be removed entirely but can be moved to help eliminate the issues you found. ‘Less seams, less problems’ is what I’ve always found with NURBS modelers…