enter image description hereI'm trying to get my hands into Blender after months using Sketchup and facing the limitations of that last one (subtracting shapes is limited to PRO and even in pro, it is still quite limited).

I first tried to export a collada file but then I read that maybe my objects are not plain.

So I did what I usually do when I check my stl files for 3d printing, I repaired them, and then re-exported them through collada and Imported then into Blender.

Unfortunately, I still can't do the subtraction.

Surely somebody here will tell me what's wrong? Maybe the whole approach?

I attached the blend file (2.6 version) so some charitable person could have a quick look and spare me light years of trial and error?


Resolved. Thanks to @Mr Zak for his help! (See second comment)

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    $\begingroup$ Welcome to Blender.SE Laurent! Could you please add some more information as to what you are doing that is not working, maybe some screenshots or a .blend? Thanks! $\endgroup$
    – PGmath
    Nov 17, 2015 at 21:14
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    $\begingroup$ Removing double vertices from both spiral and cone (in Edit mode select all and W > Remove Doubles) should make the boolean to work just nicely. $\endgroup$
    – Mr Zak
    Nov 17, 2015 at 21:33
  • $\begingroup$ Hi @PGmath, I did, check the link to google drive, it let you download the .blend file. Adding a screenshot right now! $\endgroup$ Nov 17, 2015 at 23:53
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    $\begingroup$ just for the record: light years is a distance measure, not time $\endgroup$
    – arvere
    Nov 18, 2015 at 2:43
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    $\begingroup$ @gustavofritsch, I agree, I was talking about the total distance my mouse cursor would have traveled before I'd figured this one out on my own. Sorry for the confusion :-) $\endgroup$ Nov 18, 2015 at 18:02

1 Answer 1


Your mesh has to be non-manifold. I had troubles with this as well. Removing doubles it typically a good way to start achieving non-manifoldness. There are enough tutorials out there and somewhere in the documentation there's a hint, that your volume has to be non-manifold for the boolean stuff to work properly.


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