Don't burn me at the stake please...Thread Question

[garredondojr]

Ok so as the title states I know this is frowned upon but I have a question on threading. My hobby lathe doesn't support 28 tpi threads so on my personally stuff I've been doing 24tpi on most as it's mine so who cares. but I have a good friend who wants me to thread 2 of his 22's he obviously wants 1/2x28.

So my question is if I dialed in the barrel (I have range rods) profiled the tenon, shoulder and relief in the lathe then used a die will it really be that bad? conversely would making him thread protectors if I faced, drilled, reamed, and beveled the hole and tapped it by hand with the tailstock loosened so it slides as the thread is cut be ok?

Thanks in advance.

oh and if someone has a lathemaster 8x14 that has the gear combo to do a 28 tpi that would save me a lot of hassle.
Thanks, George

[John A.]

While I like a single point cut thread on a lathe, you can turn the parts down using the lathe, and then thread it by hand. Long as you don't really require perfect concentricity.

Using a thread starter bushing in the correct caliber is also very helpful.

https://www.ebay.com/itm/1-2-28-RH-Thre ... SweadbK9HU

[garredondojr]

While I like a single point cut thread on a lathe, you can turn the parts down using the lathe, and then thread it by hand. Long as you don't really require perfect concentricity.

Using a thread starter bushing in the correct caliber is also very helpful.

https://www.ebay.com/itm/1-2-28-RH-Thre ... SweadbK9HU

hmm never seen one of those before thanks for the heads up John. i'll relay the info to him and see if he wants to proceed.

So you do have me worried about the threads being concentric. if they were off slightly do you think the shoulder would still keep the the can concentric to the bore considering that the tenon was true to the bore or can it still cut an oblong thread?

[John A.]

Yes, you can still thread it crooked by hand of course.

But before I got a lathe, I've done some really nice threads with a tap and thread starter tool thing.

Here's a 14-1 LH thread that I did on my SKS when I was converting it to the bullpup



2nd from the left




And here's a surplus M9 barrel that I threaded and used on my Beretta Centurion



While it's still possible to screw it up, with the thread starter, does reduce the likelihood some. Just take your time and keep everything as straight as possible. Especially the first thread or two. If you get them straight, the rest of them will be straight. Screw the first thread or two up, and you don't need me to tell you the rest of them will be screwed up too.

It's also my opinion that if you can keep the OD of the barrel on the larger side of the major diameter spec, has less slop for the tap to move around and has better chances to grab a thread straight.

[T-Rex]

You should be able to achieve your goal, using your described method.
A tap and die are fine to use for this purpose.
So long as everything is setup correctly on the lathe, concentricity shouldn't be a worry.
As far as threading the barrel with a die, happens all the time. I've seen a die handle locked into the tool post, centered, and used in this manner.
I'm not familiar w/ your equipment, but if you can leave the spindle in neutral and drive by hand, I think it would be a bit more controllable. Whatever you're most comfortable with.

[Capt. Link.]

garredondojr

You can cut fairly good threads that are concentric if you build a tool first.Build a die holder with a center drilled hole in it.You cut a long spud that just fits in the bore/muzzle and put it in the holder with the die.Center the muzzle using your rod and turn the muzzle to size.Insert the spud into muzzle and thread with care.They sell variants for a no lathe threading on AKs and such.
-CL

[garredondojr]

Thanks for the tips and idea's guys.

T-rex I think I understand what your getting at and no my machine isn't capable of that. I can turn the chuck by hand but the carriage is always locked in so either you turn the knob or drive it with the half nut engaged via gears.

capt. thanks for the idea on the tool holder. I understand the spud (pilot) and all but how would one go about cutting the die holder? I don't have a mill and I'm not sure if I'm up to the task of broaching it in on the lathe.

[T-Rex]

This is what I got from the Capt's description. (I added the set screws )



It's like what I described, except there's no need to make any parts and the die holder handle can be locked into the toolpost. You can make a threaded part, with a center hole, to use as a setup jig and ensure center.

I do enjoy making jigs, though

[Capt. Link.]

garredondojr these are normally lathe jobs plus a little drilling and tapping.I have also seen them as threaded rods with one end turned into a spud and the die rides the thread. T-rex your the best thank you for the illustration.
-CL

[garredondojr]

ok I get it now after looking at john's photo I realized that dies are offered round. My set is 12 point shaped (snap on) so I assumed that was the norm.

[John A.]

ok I get it now after looking at john's photo I realized that dies are offered round. My set is 12 point shaped (snap on) so I assumed that was the norm.

I would actually like that a lot better.

[ECCO Machine]

ok I get it now after looking at john's photo I realized that dies are offered round. My set is 12 point shaped (snap on) so I assumed that was the norm.

Your typical hex die (or the snap-on variant you have) are more thread chasers than thread cutting dies. Yes, they'll cut threads, but not as cleanly as a proper threading die.

It's OK to die thread a muzzle if you set up and execute correctly. The various ways of aligning detailed above are helpful, but the most important thing for axial and concentric alignment of a suppressor is the shoulder. If your shoulder is true and the threads have enough clearance, you'll align just fine even if the threads aren't perfectly true. I would suggest using an adjustable die and cutting to class 2A or even class 1A.