Weird behaviour when subtracting cylinders to sphere

[Pa Dalton]

I want to subtract 4 cylinders from a hemisphere. The four cylinders are aligned to (1,0,0), (-1,0,0), (0,1,0), (0,-1,0) and do intersect.

When intersecting one part won't be subtracted!

Whit non-intersecting cones I get the following as expected!

In case I use cylinders instead of cones everything works fine.

Maybe you can help me out :)

[Jeremy Wright]

I'm not set up to use OCP VSCode so I can't try your code, but you could try unioning all the cylinders together before cutting them from the hemisphere.

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[Pa Dalton]

Unfortunately this also doesn't work: the cones won't unite correctly.

[Jeremy Wright]

I meant to union the cylinders. The cones may not be touching correctly to union.

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[Pa Dalton]

As I said in the original post, using cylinders it works, but it is not what I want to achieve. 

I need it working with cones. 

I also tried using CQ-Editor: the problem is identical.

[Jeremy Wright]

Can you ensure that there is a little bit of intersection between the cone volumes, or will that not work with your design? It doesn't have to be much overlap, just a tiny bit should allow the cones to fuse properly.

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[Pa Dalton]

The cones do pairwise overlap (they aren't tangent to each other): the problem seems to be in the intersection of cone (-1,0,0) and (0,-1,0). 

[Pa Dalton]

Yes! 

I managed to fix it. The less rotations I perform, the less issues I get!

- I changed my align function performing only 1 rotation instead of 2.

- I made my cones intersect at the origin instead of cutting the top.

The corrections can be found in code.py adapted for cq-editor.

But, this fixes only nice coordinates. If I use (-1,1,1),  (1,-1,1),  (1,1,-1) the issue still remains. :(

[Pa Dalton]

Ok, I found the solution:

I need the tips of the cone to intersect, so, instead of using a radius = 0 , i need to pick something bigger (eg. 0.1).

At this point any cone will work.

Many thanks Jeremy Wright for your help and for responding so fast!

Have a nice day!