Dusty Stevens
Shiner
The thing i like about chickenserts is once the tool touches the crest of the thread youre doneSo to channel @Dusty Stevens, would those be called "chicken inserts"?
Threading barrels
- Thread starter Rockchuck
- Start date
That is appealing. No having to keep track of how far you are cutting.
There are soooo many ways to do things. Today I showed the kid who will be running the second lathe how to thread a muzzle. He asked too many of the wrong kind of questions. You know, "why not do it this way" when it's six of one and a half dozen of the other, then arguing when you tell him.
I finally told him that as long as he met spec, it looked good, and he didn't crash the lathe; that he could do it any way he wants..........
I finally told him that as long as he met spec, it looked good, and he didn't crash the lathe; that he could do it any way he wants..........
TylerFromMS
Gold $$ Contributor
If those are the wrong kind of questions, then it's a teaching problem, not a learning one.
There's nothing worse than someone who blindly believes and follows what he was told for the next 40yrs without ever questioning whether it was the best or even right way to begin with.
To give the benefit of the doubt, I am going to assume the above comments are reflective of a misunderstanding my post, where I perhaps wasn't as specific as I could have been when describing the student.
I have a lot of years teaching kids how to fly USAF jets, successfully, and though flying jets is much more complex and dangerous than lathe operations, the same principles apply to learning most things where errors can injure you.
When you are first learning and have zero experience, you need to ask mostly "HOW" and "WHAT" questions. You can't possibly ask an intelligent WHY question until you understand at least the basic HOW and WHAT.
Students who incessantly ask WHY before they even know HOW or WHAT, and then ARGUE with you when you give a WHY answer, aren't looking to learn. They are trying to one up the instructor and show off. It's very immature and counterproductive. Or else incredibly unaware. In my former line of work it was dangerous and such students were eliminated from the program.
Now WHY questions are fine and good after a little experience is gained and the HOW and WHAT is at least somewhat understood. I am big on explaining the WHY earlier than most, so if a student gets pushback from me on a WHY question, they are way out of line.
So many of his his questions were indeed the wrong kind of questions for this point in his training.
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He started out doing different stuff and has picked it up all very quickly. He is doing excellent work bedding stocks. He is very smart and we are working him into the lathe. He just has a few annoying traits to work out. Even more that me.......
Often, the most talented workers are a little harder to break in, and this kid is worth it.
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I just got in and plumbed up a new Carmex holder for the Mazak. I've got all external tools but my grooving tool switched over to thru tool coolant now. It just makes inserts last longer.
On the Hardinge I've always used a Mitsubishi laydown. With it I usually just use the cross slide and feed toward the chuck 6-800 rpm. On the Mazak there are different cycles depending on what you're doing.
On the Hardinge I've always used a Mitsubishi laydown. With it I usually just use the cross slide and feed toward the chuck 6-800 rpm. On the Mazak there are different cycles depending on what you're doing.
FireMedic
Silver $$ Contributor
Here is one I did today. A dial indicator with a mighty mag holder tells me when to cut out the half nut and back off the cross slide.
I like to leave as much meat around the chamber as possible. No relief grooves for me. And if I need to set the barrel back down the road, the job looks seamless.
I like to leave as much meat around the chamber as possible. No relief grooves for me. And if I need to set the barrel back down the road, the job looks seamless.
Attachments
I noticed early on that with an 18 TPI BAT SV or BAT B, it was hard to get the action the thread on all the way to the shoulder when threading all the way to the shoulder.
The BAT SV was the first action I threaded for, and the B was next. I avoided cutting a relief groove, but then I would always have to come back and cut away some of the threads. The challenge of course was cutting back the threads at the shoulder without rolling the last thread I wanted to keep.
I found a very sharply angled insert and that helped. Better than that was to come back with a parting tool and cut away the threads with that. However, the best practice was just to cut a relief groove before threading--like BAT tells you to do.
With the 16 TPI threads on a BAT M, no relief groove is needed unless you have to cut the shoulder back a turn to time the muzzle to up.
For actions with a sandwiched recoil lug, no relief groove is needed. Also, it's good to leave .125" or so of full diameter unthreaded, tenon depending on lug width, to support an align the lug.
You can look at an action and tell how much if any relief groove is helpful. So far I have threaded and chambered BAT SV, B, M, Igniter long and short, Vesper; New M-70 (CRF), Rem 700, Christensen, RBROS, Terminus Zeus and Kratos Lite, Howa, and Tikka. That covers M26 1.5, 28 TPI, 18 TPI, and 16 TPI.
As to muzzles I have threaded 36 TPI, 32 TPI, 28 TPI, and 24 TPI.
The best practice is different for each. In general, a relief groove works very well for everything but sandwiched recoil lugs. As to the concern about setting back a barrel, if you must do it, there is no issue setting a barrel back one turn even if it has a relief groove.
I guess we all figure out the way they works best for us.....
The BAT SV was the first action I threaded for, and the B was next. I avoided cutting a relief groove, but then I would always have to come back and cut away some of the threads. The challenge of course was cutting back the threads at the shoulder without rolling the last thread I wanted to keep.
I found a very sharply angled insert and that helped. Better than that was to come back with a parting tool and cut away the threads with that. However, the best practice was just to cut a relief groove before threading--like BAT tells you to do.
With the 16 TPI threads on a BAT M, no relief groove is needed unless you have to cut the shoulder back a turn to time the muzzle to up.
For actions with a sandwiched recoil lug, no relief groove is needed. Also, it's good to leave .125" or so of full diameter unthreaded, tenon depending on lug width, to support an align the lug.
You can look at an action and tell how much if any relief groove is helpful. So far I have threaded and chambered BAT SV, B, M, Igniter long and short, Vesper; New M-70 (CRF), Rem 700, Christensen, RBROS, Terminus Zeus and Kratos Lite, Howa, and Tikka. That covers M26 1.5, 28 TPI, 18 TPI, and 16 TPI.
As to muzzles I have threaded 36 TPI, 32 TPI, 28 TPI, and 24 TPI.
The best practice is different for each. In general, a relief groove works very well for everything but sandwiched recoil lugs. As to the concern about setting back a barrel, if you must do it, there is no issue setting a barrel back one turn even if it has a relief groove.
I guess we all figure out the way they works best for us.....
Which 6J did you use on your TBAS?
Thank you for the response.
So, you are running 2 lathes with TBAS? I am thinking about trying one in my rebadged Eisen 1440ev
FireMedic
Silver $$ Contributor
I had one on my precision Mathews 1440tv, which is the same machine as the eisen 1440ev. When I moved, I sold it and ended up buying a couple acra lathes. I’d highly recommend acra machinery.
The 1440ev is the bare minimum I’d recommend for the tbas. More mass is better.
I really like the tbas for action trueing and chambering dies. I’d own one for those purposes even if I went back to chambering with an inboard/outboard spider
Most of my chambering gets done on the larger 1440 acra with tbas. My 1340 stays set up with a 5c collet chuck most of the time for other things around the shop.
The 1440ev is the bare minimum I’d recommend for the tbas. More mass is better.
I really like the tbas for action trueing and chambering dies. I’d own one for those purposes even if I went back to chambering with an inboard/outboard spider
Most of my chambering gets done on the larger 1440 acra with tbas. My 1340 stays set up with a 5c collet chuck most of the time for other things around the shop.
Dusty Stevens
Shiner
Bat doesnt tell you to cut a relief groove. They say to cut full thread depth to within .100 of the shoulder
Doug Beach
Silver $$ Contributor
There’s good reasons on occasion to cut a relief, and occasions not to. If someone has any actual, verified accuracy or safety data supporting one over the other, I’d like to see it. Otherwise do what you like, that works for the job at hand. Seems like a simple idea. We like to argue.
Which is a relief groove. I know for a fact that is what Bruce and Daryle are saying. They have said it to me directly.........
LVLAaron
Gold $$ Contributor
Someone asked me privately what inserts I use so I'll share it here as well for posterity.
I use Carmex BXC grade inserts. You can thread as slow as you want and they still cut beautifully.
Internal threading tool - https://www.mscdirect.com/product/details/05765664
External threading tool - https://www.mscdirect.com/product/details/05765631
32TPI insert https://www.mscdirect.com/product/details/05765748
18TPI insert https://www.mscdirect.com/product/details/05765771
20TPI insert https://www.mscdirect.com/product/details/05765763
16TPI insert https://www.mscdirect.com/product/details/05765789
I use Carmex BXC grade inserts. You can thread as slow as you want and they still cut beautifully.
Internal threading tool - https://www.mscdirect.com/product/details/05765664
External threading tool - https://www.mscdirect.com/product/details/05765631
32TPI insert https://www.mscdirect.com/product/details/05765748
18TPI insert https://www.mscdirect.com/product/details/05765771
20TPI insert https://www.mscdirect.com/product/details/05765763
16TPI insert https://www.mscdirect.com/product/details/05765789
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