"Bob May" wrote in message
...
The purpose of the 29 deg. for the compound is to allow for the heavy cut
to
be on one side of the threads while just dusting the other side. In
truth,
you can set the compound at any angle you desire and do the cutting as you
deisre. Some ways are just easier to do than others.
Personally, I set the compound whereever it is and work from there.

--
Bob May

Bob,
That can get you in trouble, especially if you're chasing a thread that will
engage a long nut. When you single point thread, the whole idea of
offsetting the compound as we do, aside from chip flow, is to keep the
carriage loaded against the lead screw. That's why you set the compound
differently for internal threading as opposed to external threading, or
differently for left as opposed to right hand threads.

What can happen is when you feed the compound on the wrong flank of the
thread, the pressure of the cut can overcome the friction of the carriage
and move it away from the screw, and it often does. The net result is
what is termed a drunken thread. The pitch diameter may be correct, but
the lead won't be, and the thread binds in the nut. It's a smart policy
to always set your compound appropriately for the thread being single
pointed.

Harold