Hi Michael,

yes, ShrinkTrimmedSrf was one of the 2 points I raised. I look at the video again and ounce he did all the boolean diff, he separated the resulting solid even if every thing looked fine, use shrink and rejoin everything back together into a solid. Since he activated show points, it was obvious the shrink command had an effect. If I remember correctly, this was threaded part of the screw and he did the same procedure on the head of the screw before using union on the 2 parts.

I just wonder if these additional steps where really needed and or useful in some way. Having the control points on make's it obvious that shrinking provides a nicer underlying structure limited to the natural or actual boundaries of the object and it may be a good enough reason to do it but does it help down the line with other operations?

As for the other point I raised about why he rotated the cylinder, this was answered and I understand better why now.

I have a bad memory so I wouldn't know if these kind of detail or things to whatch for are mentioned in the docs somewhere, if not then maybe it could be a good idea to group all those little whatch for thing and maybe have some suggestion on how to prevent problems down the road.

Thanks,
Felix