Set smooth, hmmm...

Hi all,
I need to perform a boolean difference between cylinders, to model a steel chamber, but at the time of rendering I encounter problems;
Here the pics… With set smoot and autosmooth it’s almost ok, but not sufficient; increasing the cylinder vertices number helps a bit but does not solve:
Without autosmooth it gives really strange results:
A closeup with the vertices and normals; I think the problem is here: when I create the hole some triangular faces appear, that althought are ok geometrically , nevertheless they drive ‘set smooth’ in error:

Similar results are obtained with the blender 2.41 booleans and with the megaboolean script.
Is there a solution to obtain smooth nice-looking drilled cylinders?
Maybe I have to remove some edges, or merge faces with the same orientation (that share a ‘false’ edge), but I don’t know how to do, and if possible would like to avoid manual intervention, as the final mesh will have a lot of holes.

Does anybody have a hint?

Thanks, Leo

I don’t know how well this works, but try to add vertexes (create a cylinder with more sides) at the end of the big cylinder. When you boolean it will hopefully create straight connections and quads. The boolean operation has to resolve the way faces are cut. If there are no matching vertexes it will join them to the nearest vertex, just like in your object. But this is just a guess, which I think should be tested in practice…

Booleans are not good in Blender. Ton is actually working on them a bit in the CVS builds, but they have a ways to go. I suggest modelling a good hole by hand and duplicating that for the rest. Just have one set section with a hole that you can pimp out to the other cylinders.

Take at look at this thread showing how to model holes in tubes

Thank Hazza, that was it.

Thanks to all.

Ciao, Leo