Thanks Rally,Geoff, I did not want to do all the work and I did leave a lot unsaid.
Furthering the discussion and an inquiry from the other thread about set over, given everything else being equal, this is an accepted technique for cleaner threads;especially on small machines or difficult materials. Just takes a bit more to setup.
Unless it is for something very special, I will just grab an off the shelf cutting tool and holder and accept there will always be a compromise with tool geometry especially with Al., and then practice technique to help overcome the compromises. More swarf - yippee.
I love making swarf and always challenge myself to do the best I can regardless of what I am making. Practicing precision on a non precision project helps me learn technique with less tears, but no less frustration and scrap !
Just drew this up to help describe the technique, Neil