James; Good thread. (no pun intended) I'm self taught, so have always assumed that my instructor was a dummy. I set the tool angle with the little arrow shaped threading cutter grinding and centering gage. (Don't know what it's name is). Then set the compound dial to zero, run the crossfeed in to just barely touch the tenon, and zero the crossfeed dial. I use the #1 on my threading clock, and always wait for it to come back around. No reason. I've been told that you can use odds or evens, but haven't. When I have reset the crossfeed and compound for the next cut, I set the carriage about 1/2" to 1" away from the end of the tenon so that if I catch a crab engaging the leadscrew, I have time to pull it out before it can touch.
I do cut a thread relief with a parting off tool to just below the thread root diameter. I cut threads at 40 - 100 rpm. I use 40 rpm. 40 rpm gives me time to disengage the carriage without nicking the shoulder. I do just feed with my compound dial and I try the receiver a lot. I also record the compound dial reading when the thread reaches depth. A good machinest told me that he makes the last pass by feeding straight in with the crossfeed, but I haven't tried it.
I've been told that high speed tools will make a slicker cut, but I use a carbide tool and then lightly dress with a thread file.
I haven't had to recut a receiver thread, but I did make up a thread chaser tap for Remingtons from an old factory barrel that was a tight fit.
Probably more than you wanted to know. I do get long-winded.
On edit: added threads
Good hunting, Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time
Last edited by specweldtom; 08-20-2008 at 06:01 PM.