Barrel threading????

im no gunsmith, but i cant imagine they would use a die set to thread a barrel. Lathe would be my first choice. accurate down to hundredths or better with a skilled hand.
 
Yes, it's positioned on a lathe, checked to make sure it's centered properly, then the threads are cut. Depending on set up, thread, and pitch, this can take a while. Square threads on P14s and M17s for example are more difficult to do properly (at least for me, maybe I'm just slow). - dan
 
dan belisle said:
Yes, it's positioned on a lathe, checked to make sure it's centered properly, then the threads are cut. Depending on set up, thread, and pitch, this can take a while. Square threads on P14s and M17s for example are more difficult to do properly (at least for me, maybe I'm just slow). - dan
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Thanks
would they be cut using the lathe itself or cut with a conventional die attached?
 
Very difficult to cut a thread concentric with the shaft without using a lathe. Dies are only good for short threads that don't have to be concentric. If you want an accurate rifle, you want your thread on the barrel to be concentric with the BORE. Sometimes temporary centring pins, or cutting the 60 degree centres at each end of the bore with a single point tool are used.
 
It is just a 60 degree point and the comound is set for 29 1/2 degrees. When you get close to finished, you try the barrel on the receiver and if necessary remove another thous or so and check again until you have a snug fit. If the barrel already has sight dovetails or similar, you move the shoulder forward until the top of the barrel is top dead center. Finally and depending on the type of gun, you face off the back of the barrel to length and chamber.
Square threads like on rolling blocks and trapdoor springfields are a royal pain because they go from tight to loose almost instantly.

cheers mooncoon
 
There is a Canadian book called Technology of Machine Tools by Krar,Oswald,And St.Amands that covers thread cutting on a lathe among other machine tool operations.They also had a picture book that a first time user could probably do a decent job with.
Cutting square threads is easier than V threads with a properly ground tool.The compound is set parallel to the ways on the lathe adjust thread fit.Usually the depth of cut required is less than called for on a barrel print.
If you're just learning to use a lathe and intend to thread and fit a barrel try it on a piece of round stock first
I've taught a number of people to fit barrels and it was sometimes quite an experience
After you have it threaded you have to chamber it which causes some poeple problems.
Mauser and Lee Enfield threads are 55 deg Whitworth.
 
from my experiance in college. square threads are hard to do. as its very hard on the bit. very easy to break the bit. as the bit can at the cutting point. only be as wide as the gap in the thread (sorry cant remember the proper term lol) and has to be as long as the thread is deep. tool looks much like a grooving tool which is extreamly easy to break. i find it very very easy to make standard 60deg threads. i think the harder part would be getting the barrel aligned properly in a 4 jaw chuck. indicating the inside of the barrel wouldent be easy with the DTI bouncing on the rifling.
 
bits shouldnt break veery often if your feed and rpm are set properly for the type of metal you re cutting. never ran a lathe but on a mill (set up for simple/small lathe work) the only time i wrecked anything was when i got sloppy with feeds/rpm. same with endmills
 
Well any time you want to thread a barrel, whether it's the breach end or the muzzle end, you always want to make sure that the thread is true to the bore.
If it is not, some very bad things can happen if your muzzle brake has a clearance hole that is very close to the bullets diameter. Like the bullet hitting the muzzle brake on the way out. Seen this happen once. Scared the s**t out of me. :D
You never get as nice or true of a thread with a die as you do when cutting it on a lathe, plus you will always have to turn down the outer diameter of the barrel, in the area you want the thread to be, to the proper diameter specific to that thread. This has to be done on the lathe anyways so might as well cut the thread on the lathe at the same time. You can use a die to cleanup the thread after you have screw cut it till it's almost done.
I have done this a few times for a standard 1/2-28 thread most commonly found on AR15 flash hiders and muzzle brakes. Now if you don't have a proper tap because it is to expensive to purchase for one job or just not available, then you will have to screw cut the thread on the lathe completely.

If you don't have access to the proper equipment and don't have the proper experience, it's best to let a gunsmith to do it for you. For anything else I would say give it a try but when it comes to firearms you can't be too careful.
But that is just my opinion. ;) :)
 
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jester1 said:
Would it be the same for threading the muzzel end of the barrel to accept a suppressor? Lathe or die?
Thanks people much appriciated.
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Since you have it in the lathe to turn it down to size already you might as well thread it too. I don't know much about suppresors but I think it would be good if they went on straight. I am somewhat sure it is imposible to thread something crooked on a lathe, but it is easy to do it with a die, so if you were using it don't take it out of the lathe and use the tailstock to push the die while you turn the chuck by hand.
 
Basically if you want any threads on anything to be straight you do them on a lathe or a mill and you spend all the time it takes to set it up so that its true. I'm sure there are other tools available however I find these give me the most precision.
Dave
 
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if that barrel is dialed in properly on a properly leveled lathe it most definatly will be straight. if you use a die you are going to have nothing but problems..done lots of threading on lathes as i am a machinist.
 
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