Threading Barrel

[J. Valentine]

Picking up an existing thread is easy. First item is to get the old barrel running true by indicating it in. Then set your lathe up to thread 16 TPI. Back out on the crossfeed until the threading tool cannot touch anything then engage the half nut so the lathe is in gear. Let it run until it's to where the threading tool is where the threads would be if it were touching. Turn off the lathe but leave the half-nut engaged. When the lathe stops run the crossfeed in until the threading tool almost touches the thread then by working the compound set at 30 degrees and the cross feed as needed the point of the threading tool is in the bottom of a thread. Set the crossfeed at '0' and the compound at whichever number you choose. Then disengage the half-nut and back out on the crossfeed so you can move the saddle away from the headstock.

This making any sense to you? I don't know if I've done a good job of explaining it but I learned to do this while in machine shop class just by looking at it and it just came to me how to do it. It will become apparent to you when you study it for a minute or two.

Holler if you need help.

I would not disengauge the half nut the first time , just back out the cross feed after the tool is lined up , run the lathe in reverse until the tool is well clear of the first thread . Stop the lathe then run the cross feed in to the correct depth to make a first cut and start the lathe in forward at the correct spindle speed and thread feed . If you disengauge the half nut before the first pass you will have to use the thread chasing dial to reingage in the correct place to start. Thats how I do it anyway . You also have to take up any play in the screw cutting system as you move the tool into the thread form at the initial setting up. After the first cut has finished then you can disengage the half nut and return for the next cut using the thread dial to reingage.
Or if you have a instant stop foot brake , just hit the brake as you back out the tool. Run in reverse to clear the tool, stop and reset for next cut. Start in forward.