Posted: 8/5/2009 2:14:26 PM EDT
| How do you thread an un-threaded barrel? I have a AR post ban barrel and it doesn't have a threads. I was just wondering how its done. |
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Guess this isn't a machinist question?
I'll take a stab at it anyway. First thing is to remove the barrel and strip it. Next is to chuck it up in the lathe and indicate the bore to run concentric. After that, you turn the muzzle down to the proper OD for the thread, then set the lathe for the proper thread pitch, make a test cut to verify the lathe is set correctly, and then start cutting threads. Get down to about .005" to .010" away from what the books show the depth should be and start checking fit frequently. Once the threads are right, lightly touch a file to the threads to knock off burrs, and call it done. |
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Quoted:
Not a gunsmith, but you stick it in a lathe and use the properly sized tool to cut 1/2x28 threads in it. A 60 degree threading tool works fine, but inserted tooling normally requires obtaining the correct insert for the thread pitch range. ETA–– IOW, some inserts do not have enough length on the cutting edge to obtain full thread depth. |
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Quoted: Quoted: what they said.. and a nice cut off tool to make a sholder cut for the washer to hit up aginst. A standard turning tool works better. Grooving tools work better than parting tools for stuff like that too. ya ya.. but the .05 cut off tool is already set up in the jig.. just drop on and go.. Other wise i have to take the tool out of the holder swap the new tool in set the height. |
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Quoted:
Guess this isn't a machinist question? I'll take a stab at it anyway. First thing is to remove the barrel and strip it. Next is to chuck it up in the lathe and indicate the bore to run concentric. After that, you turn the muzzle down to the proper OD for the thread, then set the lathe for the proper thread pitch, make a test cut to verify the lathe is set correctly, and then start cutting threads. Get down to about .005" to .010" away from what the books show the depth should be and start checking fit frequently. Once the threads are right, lightly touch a file to the threads to knock off burrs, and call it done. This answer is detailed and correct. |