Subtract does not work, all other tools do

Dear all,

I’m chasing my tail here with two solids that work with no problem with anything, except one way of subtraction (subtraction the other way around works). I would like to “cap” the top surface to the height of 35mm. Please, help. (1.5 MB) Thank you all for your time,


I thought this was an issue with small faces that SketchUp won’t make and maybe it is. I got it to work once with the Dave method but I had to scale it up so much, 100000 times that it made the camera go all weird as if there was some object miles from the origin that I couldn’t delete.

Eneroth’s Solid tools made a better attempt. It chopped the top part off but failed to make it solid. The top face would have to be repaired by hand.

BoolTools 2 did a nice job, the difference tool worked fine first time:
Forum_gm.skp (545.6 KB)