Trouble with Boolean difference

Hello! This is my first post on the forum. I have used rhino for a few months now, but I still have a long road ahead.
I have a problem with Boolean Difference, or maybe I’m just using the wrong tool for the job.

I’m modeling a guitar neck. First I made the center block, and now I want to cut t with the shape of the grey curve.

I get “Boolean Difference has failed” all the time. I know how to use the tool because I tried with simple shapes first.
Any help is appreciated (and sorry for the bad spelling :grin: )

Hi Mat - Export the objects that you want to trim and the objects to trim with, and post the file here- you’ll get some help.


Boolean operations only work with solid bodies.
The grey part seems to be a surface. If you want to make a “boolean difference”, you need to make it a solid first.

This is not accurate… Boolean operations also work with open objects, just that it’s harder to predict the outcome. See this page for more info.


1 Like

try the command

before you might want to test the volume against your “cutter” by command
and see, if you get the expected / desired curve|Solids|_____4



Thanks! I’ll do that as soon as I get out of the office. Is there a better format to do the export?

Mi Mat - just export to a Rhino file - the idea is to avoid sending a bunch of extraneous stuff - just the bit you are asking about.


Matkat boolean.3dm (948.9 KB)

Here is the Rhino file, only with the parts I’m asking about.

Hi Mat - you can use BooleanDifference here but you’ll need to clean up a bit and make a couple of changes -

  • the solids are not all very clean - the one closest to the camera, as the file opens

has a sliver surface here:

I’ve separated the surfaces - that vertical line is a zero-width surface - you should get rid of that and make the overall side there from two surfaces that meet cleanly.

Once that is cleaned up, I’d duplicate the cutting surfaces and ExtendSrf a short distance - 2 in this case should be enough, and Join. The idea is to make sure they fully intersect the solids.

You should now be able to Boolean, however, one of the solids sill fails - you’ll need to Explode to surfaces and split/trim and Join ‘by hand’ for this one - my guess is the edge of the cutter at the rear that is coincident with the edge of the solid is what it is not happy about. (V6 handles it, btw…)

In general the way to troubleshoot Booleans, at least as a first run at it, is to Intersect the objects (not BooleanIntersection) and look at the resulting curves. And keep in mind that Trim/Split are the longhand versions of Booleans and using these on the surfaces involved can often either work when a Boolean fails, or show where the problem lies.
Matkat boolean_PG.3dm (867.0 KB)


1 Like

Wow, I’m gladly surprised of the prompt response and quality of assistance.

Thanks a lot, all of you, will try to check all the details as soon as I get back home