Don't want to derail DeHui's thread so I'll start another. When he mentioned a double start thread, Acme thread came to mind though he didn't say so.
When milling an internal two start Acme thread with the cutter shank parallel with the work, would a 29 degree cutter produce a correct thread form? Machinerys Handbood says the change in form is negligable when milling a 60 deg. thread, but I would think it would be a different story for an Acme thread.
On a non cnc mill how is the lead or tool advance provided?
These are strictly "would like to know" questions since I don't have a mill.