Cut a cylinder in two


I’m trying to cut a cylinder in two parts.

I’m trying with the method like the one on the picture.

It works well with a cube but it won’t work with this cylinder.

What is the correct/best way to achieve this please?


You could use a face to cut it as you have done (along with Intersect Faces), but because geometry sticks together in SU it’s generally easier to make a copy of something and delete half of each copy than to cut it in two. Or, start with the two halves (make a copy and delete half) as faces and extrude them after. Or start with one half, extrude it, and copy it. Really, the last thing you want to do is cut a full ring in half.


Two small points to add to Gully’s excellent explanation. When you draw the circle that will be the basis of the half-ring, rotate the circle so that one edge (not a vertex) aligns with the red or green axis. This will produce a cleaner shape once the circle is halved and extruded. Also, you may wish to set the number of sides on the circle to 48 or some even larger number, rather than use the default of 24 sides; the resulting half-cylinder will look smoother.
Hope this helps.


Thanks a lot for your answers.

To give you an idea, this is the kind of object I need to create (3D printed) - diameter is around 1,5cm.

But you gave me some ideas how to do it another way and I’ll give it a try :wink:

Thanks a lot again.


A bit hard to see why you show us this stuff now instead of in the first place.


As I said, what I build is something “like” this image but it is not this object I’m wanting to build.

Would it change the way of doing it in Sketchup?

BTW, I found this picture after I made my first post (…).

Not a big deal. The approach would be slightly different–probably a case of modeling half and copy/flip for the other.

It’s just when we tailor a response for a cylinder which turns out not to be a cylinder, it represents a sub-optimal exchange. Optimal is better, that’s all.


…sorry about that.

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