"Chief McGee" wrote in
news:duesc.19880$JC5.1768108@attbi_s54:

I agree. 1018 hrs is terrible to thread. But there are a few things
to try. You state that you turn a section to .500 dia.

Sorry finished part will be 3/8-40, I went to a test piece after the
trouble started.

... try going a little smaller. The book says you
can go to a minimum of .3691. Unless this is a very important part, I
would go to about .365 dia.. This will give you a flat on top of your
thread which should help with the burr.

I'll keep this in mind. I am trying to get as close to the "nominal" thread
form and size as possible.

Also use a small triangular
file to just kiss the burr. With the lathe running, hold the file so
that it is about 45 degrees to one side of the thread and let it ride
down the thread. Then hold it on the other side and let it ride to
the left again. Do this several times. Then, make one more pass with
the threading tool set at the final dimension that you used before you
used the file. This should clean up any burr you created with the
file.

I'll try that.

Thanks Chief,

Rob