I have a boolean Difference question. I have two shapes. I want to subtract one from the other. When I try a boolean difference I get and error and a little icon… however if I shuffle the difference object just a bit to it’s left, I can boolean just fine. See attached video and Rhino File.
I feel like there must be something wrong with my geometry but I cannot find the culprit. Does anyone have any suggestions?
Thanks!!!
QuestionBoolean.3dm (7.4 MB)
Math is the culprid. Surfaces have directions and are negative in one normal direction and positive in the other normal direction. if you have two surfaces overlaying perfectly, it is not possible to determine, what you want to keep and what not. you need tiny intersections everywhere in rhino to have boolean operations working correctly.
Also the little bubble can give more information on why the operation didn’t work if you select it and look into it’s properties.
Hope that helps
Ben
there is a naked edge in the base-Object
_showEdges
and see the 2ndary text of the dot.
fix this edge and boolean difference should work.
without testing - but mainly the workflow will be:
_extractSrf
_Untrim
_extendSrf (optional)
_trim
_join
hope this helps - kind regards -tom
Yep. This helped a lot. Thank you!
Hello Drew,
On my end, in R8, I was able to run the cap command that closed the object and then successfully run the boolean difference. I do not know why this worked or seems to have worked.
Thank you,
Andy
that s a bad workflow ! not recommended.
be careful with cap.
it might (and in this case it does) add a micro-Surface / super narrow surface stripe.
and this will give further problems down the production pipeline.
in this case the added face is something like
0.0003 x 2.7 inch
(document tolerance is 0.0001)
the minimum detail - rule of thumb - should be 10 times the document tolerance.
kind regards -tom
Hello Tom,
Thank you for the “teachable moment”. I was suspicious and that is why I prefaced my post with “…seemed to have worked.” I am going to follow your workflow and review the help section on the cap command. Likewise, advice about setting tolerances is appreciated. I may have not noticed that the presets in R8 for mesh settings were in previous versions but irrespective, I am finding them quite helpful. [and mentioning them here as I imagine they could help others]
Thank you,
Andy
