Your question started of asking for a tap. They do not make that thread any more, unless someone knows different. The best thing to do is to cut the thread on your lathe. Start out making the external threads first, then the internal internal using the external as a gauge for the fit. It not that big a deal just pay attention when cutting the threads both in and out, and the practice is good for the more you learn. the more you will be able to do.
From: Charles Tucker <1954wd45@...>
Sent: Tuesday, February 26, 2013 1:00 PM
Subject: [southbendlathe] Re: 1 1/2-8 tap needed
What you have to tap won't fit in the lathe chuck or faceplate???
> Anyone know where I can buy one at at a low cost?
> I just can see spending alot on something Im going to use only once.
> Or anyone willing to loan or rent one to me?