Muzzle threading help needed.

[6literZ]

Stob,

If I were doing the work you describe on the tenon to achieve the desired thread without a relief I would proceed as follows;

-Chuck barrel into 4 jaw chuck and zero TIR.

-Begin to cut threads, when reaching close to desired length switch power off and hand rotate chuck to finished thread length.

-Mark chuck to allow repeating the process, and possibly set up a drop indicator on the carriage for reference.

-Retract cross slide.

-Throw power switch to reverse still with half nut engaged to start of thread.

-Feed cross slide to 0 or stop.

-Advance compound to remove .005".

-Repeat process.


Is this the proper method?
(Edited to add)Would the chips bind up without tapering the threads toward the end of the cut with this method? How is this alleviated?

Thanks in advance.

 

[Stob]

You can do it that way, but it will take forever. I never power off when threading. You are correct that once a pass is made and you pull out the crossfeed, you crank the carriage back , return the crossfeed to zero and advance the compound.

The only time I stop the lathe is if I am cutting a metric thread. Once you start, you never disengage the halfnuts. You have to stop, back up tool, reverse motor, that start again.

This is the only time I would ever cut a relief.

 

[6literZ]

So at the end of the thread is the half nut being disengaged while also simultaneously reversing the cross slide so that there isn't a groove being cut by disengaging the half nut while the work is still spinning?

 

[Stob]

Exactly. You do both at the same time and the thread ends. You just need a way to know just when to do it, that's why I use a dial indicator and I watch it run down to zero, and I stop. Works great.

 

[Blackhawk]

Thakks for the post, I've been wondering about this for some time

 

[Holescreek]

A .45acp Mauser isn't exactly a bench rest gun and a beginner with a new lathe doesn't quite lay the groundwork for testing the limits of hand speed and hand eye coordination IMO. There are lots of lathes with special equipment for this and most of us don't own them. The acronym "KISS" comes to mind here.

 

[Rick Leslie]

A .45acp Mauser isn't exactly a bench rest gun and a beginner with a new lathe doesn't quite lay the groundwork for testing the limits of hand speed and hand eye coordination IMO. There are lots of lathes with special equipment for this and most of us don't own them. The acronym "KISS" comes to mind here.

That's what I'm saying. The original post was 'beginner' threading 45 ACP barrel for a Mauser. The question was 'how to and do I need' a relief area for the threads? Simple answer is no, it's not necessary. Do the easiest method, or the one you're most comfortable with. No need to debate the merits of relief vs. non relief threading, etc.

Although, I did like the info on the threading clutch that came from the discussion. Looks like a great mod.

 

[6literZ]

I did some practice cuts, and found a few flaws.

First off, after a few cuts I noticed my compound which I had set at 29.5 was not cutting correctly. I've read about the issues before and set it to 59 degrees.

I attempted to continue and see if it could be salvaged, but I think the major diameter was already too small. I continued anyway for practice and when I checked with the thread pitch mic it was way too small.













I was using these specs for a 45acp.





The threads threads are rough. I used wd40 to cut. I don't know if being an old junky surplus
Mauser barrel has anything to do with the cut. What can I do to get smoother cuts?

 

[Blackhawk]

dont know what kind of lathe you have, I have a precesiom Mathews 12x36 and was told not to use the guage because it it was not accurate, I now use a protractor and it produces better threads. I was having problems using compound but according to darkzero, don't use the compound, just drive straight in, and it worked for me. I'm now threading gun barrels. I still occasionally hit the shoulder once in a while, got to work on that

lanham​

 

[Stob]

When you set the threading tool with the fishtail, simply pull the tool back and see if it follows the angle in the fishtail. I only thread straight in when internal threading, because my compound won't swing around to do it. Checking with a protractor is a great idea, then mark something so you can repeat it.

WD40 is not cutting oil. Go to Home Depot or Lowes and by some dark theading oil in the plumbing section, preferably Rigid brand.