Boolean difference problems

… working on a Saturday on the solid (shown in orange) -running boolean difference to create slots in it using the grey polysurfaces that are grouped together. Have tried over and over again and it fails. Dir is correct. Have tried tightening and loosening tolerance. Nothing helps. Any suggestions would be appreciated. Thank you.How to boolean diff these.3dm (4.0 MB)

Ungroup your vent holes and delete the stacked duplicates does the trick. I then used create solid, locked the main part and deleted the unwanted solids.

Hmmm… I see that I had duplicate trimmers (the grey objects) – good point – although I wonder why seldup didn’t catch that?

I’m not following the rest of your workflow, though. When you say “I then used create solid” – on what? The orange object was solid, wasn’t it?

Thank you.

Use create solid on all the objects at once. Then lock the main slab and delete all the vent hole solids.

I don’t think SelDup will work if the Dup is grouped.


No-- Seldup does not find them even when they’re ungrouped. I’ve attached a file with just the curves on it. Each curve has a duplicate on it, exact size, shape and position. Running seldup does not catch it. Any thoughts?Seldup.3dm (404.0 KB)

Weird… I don’t know what’s going on. I tried Ungroup a couple more times (sometimes you can get nested groupings, but that wasn’t the case here) and that didn’t change anything. I selected everything and exploded it, and then SelDup worked on the individual curve segments. Joined them back together, and SelDup stopped working. I copied everything in place and put it on a new layer, wondering if it had something to do with being on a sublayer, but that didn’t make any difference, either.
I’m stumped. The only thing I’d experienced was having a duplicated component grouped and SelDup not finding it, and it worked after Ungrouping, but this example didn’t act this way. I hope one of the McNeel gurus will have an answer.
Good luck with this,Doug

Other than rebuild for what didn’t update, on dupes, if you try offset and click a curve it should give a popup to choose a way to show them an idea.

Keep in mind that SelDup is looking for exact duplicates, it does not have any ability to locate awfully durn close. The point locations of these curves are microscopically different. They are also in opposite directions, so the points are reordered.

ON_PolylineCurve: domain = [0,5.83605]
point[ 0] = (-35.614268640054725, 821.19213708385553, 286.69175278057946), 0
point[ 1] = (-35.506411833665403, 818.65949244161652, 286.8495573121329), 2.54755
point[ 2] = (-35.876653050945556, 818.64724194535495, 286.84953059313608), 2.91799
point[ 3] = (-35.984509857334992, 821.17988658759691, 286.69120098200233), 5.46561
point[ 4] = (-35.614268640054725, 821.19213708385553, 286.69175278057946), 5.83605

ON_PolylineCurve: domain = [0,5.83605]
point[ 0] = (-35.614268640054682, 821.19213708385507, 286.69175278057969), 0
point[ 1] = (-35.984509857334992, 821.17988658759691, 286.69120098200233), 0.370444
point[ 2] = (-35.876653050945585, 818.6472419453554, 286.84953059313614), 2.91806
point[ 3] = (-35.506411833665403, 818.65949244161652, 286.8495573121329), 3.28851
point[ 4] = (-35.614268640054682, 821.19213708385507, 286.69175278057969), 5.83605


I understand Pascal- and it makes sense. I’m sure that you’ve been asked before, I wonder what it would take to be able to adjust the sensitivity of seldup, so that it can find things that are close but not identical?

For example, with settings that would allow you to ignore directions, or number of points in a cruve… or with a slider that allows you to find similar objects that may be positioned slightly off?

I have a feeling that it’s easier said than done: )

Yeah, it is - & it is a long standing request… somehow it never makes it to the top of the heap.


  1. Trimmed with rectangle (from reight view)
  2. Command _Cap (creates solid’s for Boolean Diffrence)
  3. Boolean Difference (doubles not decisive, are removed by boolean)
    How to boolean diff (781.5 KB):

I’m having this issue as well, both the generation on unwanted dup and the inability to select them although they appear to be the same and all came from somewhere besides my efforts. It’s maddening to continually come into a list of possible selections on curves that have been left alone for as much as a day. There’s something very wrong going on here.