Hi jack, yes that's correct you can't use Extrude currently on your cylinder case because Extrude generates a result that goes in one single direction vector. It doesn't necessarily have to be a flat surface, it can be a curved surface like this:



Then extrude of that will make this result:



For Extrude the "side walls" are all straight lines going in one single common direction:



But for the cylinder that's not going to work, the cylinder needs an offset surface constructed which makes a surface that is displaced along the original's surface normal and not just in one single direction.

I just wanted to mention that if you have some other situation where extrude would do what you need then a quick way is to use Trim to cut up a face of a solid and then select the face to extrude, then you get the automatic boolean without any added steps for "delete outer face" and join. That's the one that does the quickest "push/pull" type action currently.

- Michael

There is another one very speedy but... :)

The Flow Function

"... thx, but not a speedy way."

Just to be clear, you changed your images after I replied. I was responding to the vertical slot and using boolean diff to create it.

If performing a simple boolean operation is not speedy enough, then I don't know what is.

To address your latest images:

I would have created the cylinder in MoI with the horizontal groove in a single operation using Revolve with a profile curve that included a notch for the groove.
Then create each vertical groove by extruding a rectangle and Boolean Diff with the cylinder.

Practice will make very speedy.

Ed Ferguson

I think this caused by misunderstanding, but thank you sincerely.

I tried all method in this thread, use "Shell" fit my purpose.