AR Sponsor
Posted: 6/20/2014 6:04:06 AM EDT
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Just got myself a lathe big enough to mount a barrel between centers.
What's the best way to get a center on the chamber end of an AR 15 barrel? Or does everyone just mount the barrel extension in the chuck and put a live center on the muzzle end? I've got live and dead centers and lathe dogs to drive the barrel if need be. |
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Quoted:
What are you trying to do to the barrel? Cut threads for the muzzle and do a little profiling. I usually hear people say they put AR15 barrels between centers for threading, but never knew how they actually manage to put a center, live or otherwise, on the chamber end. I'd be hesitant to put a dead center anywhere in or near the camber. The best I can think of it getting a soft nosed live center and cutting it to fit in the chamber. |
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Quoted:
Just got myself a lathe big enough to mount a barrel between centers. What's the best way to get a center on the chamber end of an AR 15 barrel? Or does everyone just mount the barrel extension in the chuck and put a live center on the muzzle end? I've got live and dead centers and lathe dogs to drive the barrel if need be. Chuck the breech end in a 4-jaw and use indicators to center it. If you're actually trying to center on the bore, you'll need to use the 4-jaw for the breech and a live center with crown protector for the muzzle, and may need to offset the tailstock - depends on how concentric the barrel is to the bore as it sits... Profiling cuts in such a setup are sure to require a steady rest or follow rest or you'll be deflecting big time near the middle. |
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So when someone says they're putting it between centers it's just as likely that they chucked it up on the breech side and put a live center in the muzzle?
How do you know you've got the bore fairly well centered when it's chucked? The best that tells you is that the barrel extension is centered, right? |
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Quoted:
So when someone says they're putting it between centers it's just as likely that they chucked it up on the breech side and put a live center in the muzzle? How do you know you've got the bore fairly well centered when it's chucked? The best that tells you is that the barrel extension is centered, right? Correct. And if they didn't use a crown protector, they may have marred the crown some with the steel live center nose taper. If the barrel and extension happen to be perfectly concentric to the bore, then it's all gravy; but for real precision, you cannot make that concentricity assumption. In practice, simply chucking at the extension and using a live center at the muzzle will keep it concentric enough for a brake or flash suppressor, but might deviate enough to make it problematic for a high dollar sound suppressor, depending on the suppressor's freebore. |
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Quoted:
So when someone says they're putting it between centers it's just as likely that they chucked it up on the breech side and put a live center in the muzzle? How do you know you've got the bore fairly well centered when it's chucked? The best that tells you is that the barrel extension is centered, right? It is rather imprecise and why I try to avoid doing it that way. |
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Quoted:
Correct. And if they didn't use a crown protector, they may have marred the crown some with the steel live center nose taper. If the barrel and extension happen to be perfectly concentric to the bore, then it's all gravy; but for real precision, you cannot make that concentricity assumption. In practice, simply chucking at the extension and using a live center at the muzzle will keep it concentric enough for a brake or flash suppressor, but might deviate enough to make it problematic for a high dollar sound suppressor, depending on the suppressor's freebore. Quoted:
Quoted:
So when someone says they're putting it between centers it's just as likely that they chucked it up on the breech side and put a live center in the muzzle? How do you know you've got the bore fairly well centered when it's chucked? The best that tells you is that the barrel extension is centered, right? Correct. And if they didn't use a crown protector, they may have marred the crown some with the steel live center nose taper. If the barrel and extension happen to be perfectly concentric to the bore, then it's all gravy; but for real precision, you cannot make that concentricity assumption. In practice, simply chucking at the extension and using a live center at the muzzle will keep it concentric enough for a brake or flash suppressor, but might deviate enough to make it problematic for a high dollar sound suppressor, depending on the suppressor's freebore. You're the man, thank you! 
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