How to cut out a piece of a model?

[Anonymous]

I'm trying to cut out the middle of the model as a standalone cylindrical piece.

I've already used booleans - difference to make a hole in the center, but this same method is not working (Photo with all geometry covered except for the center) for the other way around because the models dissappear afterwards. I've tried troubleshooting the normal booleans things; freeze transformations, delete history, make the models bigger, etc.

Does anyone have any suggestions on how to cut out just the circular piece?

I'm going to 3D print this so the method doesn't have to be mesh friendly by Maya standards as long as the model is still waterlocked.

Thanks in advance!

[hamsterHamster]

The model looks like combo of shapes put under one transform, which, I am afraid, booleans won't handle. Ensure it isn't so - Separate, then boolean-Unite every separated part into one watertight mesh; only then do the cutting.

Also, won't work always, but sometimes it does - if the mesh disappears, you still have the transform nodes in the Outliner - move that leftover of the cylindrical piece up/down until the mesh re-appears.

If all bool-ing fail, run Mesh>Cleanup to detect/mend incorrect topology, which also is likely to cause troubles.