Hi Michael,

I'm working on a pretty straightforward (to me at least) piece of mechanical design, but I keep encountering boolean issues - specifically "Unions" not working or creating strange overlapping surfaces. I'm attaching the most recent example - a trimming object I was trying to Union so I could use the unioned object in a later boolean difference operation.

I'm also attaching a screengrab of the trimming object in relation to the object to be trimmed - in case that helps...

Any sense of why the boolean op isn't working here?

Thanks - as always for the insight and assistance.

Select your "Cylinder" : function "Join" = all facettes of the object (here cylinder)will be joined !

And now your Bolean union "Box Rectangle" + Cylinder will be fine :)
If one of your piece is not entire, boolean will be hard!

Hi Satoribomb,

There is a small mis-alignment between these 2 shapes:




Intersections with overlapping pieces and along shared tangents tends to be a delicate area, and small misalignments like this tend to make the calculations much more difficult, even between pretty simple shapes.

If you delete the cylinder and draw a new one snapped directly on to points of the box (just with Draw solid / Cylinder), then those will boolean together ok - I have attached the redrawn cylinder here as Trimmer_fixed.zip .

But still after that, that piece won't boolean difference away from the main body - there is a different sort of problem with the main body that I will explain in just a minute in another post.

- Michael

Hi Satoribomb - this is the other problem area in this model. There is one spot on the main body that has a darkened line along it. At first it looks like an edge:



But it isn't an edge - it is an area where the surface is folded in a slight zig-zag back on itself. Here I turned on control points for the surface and moved the 2 out of order ones slightly out of line with one another so you can see what I mean:



That kind of zig-zag fold in the middle of a surface is also going to generally hose operations that try to do surface/surface intersections like the booleans. There's the same thing on the opposite side as well.

If you have some of the earlier stages of this model saved off, you might go back and see if that zig-zag was in one of your original drawn curves or not - it's possible that it was created by some bug in a construct command, or it could also have been accidentally created by you when placing or moving points...

Unfortunately anything involving intersections is not very tolerant of these little perturbations.

Thanks for posting your .3dm file - that makes it much easier to see what is going on.

- Michael

Hey Michael - hhanks for noticing the little anomalies. Guess I'll have to redo the sweep I used to make the base object and fix the mis-aligned cylinder on the trimmer... :P

More importantly, when I encounter these issues going forward, I'll first need to check my geometry for those 'little' imperfections.

Thanks again.