Re: Anybody know how to make a barrel vice?
My barrel vise system has evolved to get a grip on the barrel adequate for 600 foot pounds of torque for old rusted up surplus rifles. [After having snapped off a number of grade five 1/2-13 bolts]
I put two steel blocks, 2"x2"x6" on the face plate of the lathe, gapping the two blocks with a 0.125" spacer. I then drill and bore a 1.5" hole.
The vise is drilled and tapped for 1/2-13 threads on the bottom of the bottom block, to clamp to a 1/2" thick steel bench top.
The top of the bottom block is drilled and tapped for 7/8-14 threads.
The top block is clearanced for 7/8-14 threaded rod.
I buy 1.5" diameter 6061 Aluminum round stock from MSC in 6 foot lengths. From this I make collets. Some of them are internally tapered to match the barrel shank's taper.
The 7/8-14 nuts are tightened with a 3/4" drive socket wrench with a 16" handle, and I pull on that wrench as hard as I can. That pencils out to a clamping force of ~100,000 pounds. Meanwhile the shear at the barrel- collet interface at the threshold of slipping is ~15,000 pounds. That mean we have a lousy coefficient of friction [remember, from grade school?], so I put powdered sugar there.
Here is a video where I measure the torque needed to unscrew a 91/30 barrel after 73 years. You can skip the 1 minute video, the answer is 540 foot pounds.
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Q: How long does it take a 60 year old man to hack saw through 2"x2" pieces of steel?
A: 10 minutes for the first cut, 20 minutes for the second cut.