Hi Steve,

> Till this time I used Boolean Diff/Union is there a difference
> between this and edit/trim/join

Trim and join are sort of more "low level" tools than the booleans.

You might kind of think of the booleans as a sort of batch mode trim & join where they do a similar job but automatically decide which pieces to discard from the trimming according to what volume they are contained inside of.

Trim will cut things up but then it's up to you to pick which pieces you want to discard, and then you will need to follow it up with a Join afterwards - those steps are basically built in to the booleans so it's sort of more convenient to use the booleans when possible (which is basically when you are working with solids).


> Till this time I used Boolean Diff/Union

You could still use boolean union in this case if you made the pieces stick through each other a little bit instead of having that side piece sort of exactly skimming along the outer surface of the main body - it's that skimming situation that the booleans are having difficulty with in your particular case here, when they try to intersect the 2 surfaces they are not getting a clean intersection result because the side surface has just a tiny amount of empty space between it and the main body in a few areas.

- Michael