Making a sharps barrel in my lathe.

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redneckalbertan
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Re: Making a sharps barrel in my lathe.

Post by redneckalbertan » Mon Nov 17, 2014 8:38 pm

I don't know how it was done in industry, but should you profile the barrel before you bore it and put the grooves in? Just thinking about the release of stress when you mill the profile of the barrel. I have no clue on the proper order of operations, just thinking outloud.

hammermill
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Re: Making a sharps barrel in my lathe.

Post by hammermill » Mon Nov 17, 2014 10:05 pm

Most barrels are blanks,profiled and such after purchase.

Harold_V
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Re: Making a sharps barrel in my lathe.

Post by Harold_V » Mon Nov 17, 2014 10:57 pm

Yep, what hammermill said. I recall watching P.O. Ackley straightening a barrel after it was machined for profile.

Harold
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redneckalbertan
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Re: Making a sharps barrel in my lathe.

Post by redneckalbertan » Mon Nov 17, 2014 11:12 pm

Thank you gentlemen, it's always good to learn something! How straight does the barrell have to be? How does one straighten it? and How does one check straightness, by eye or with a dial indicator?

homebrew .357
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Re: Making a sharps barrel in my lathe.

Post by homebrew .357 » Tue Nov 18, 2014 2:05 am

The thing is, this is a BB , I`s 1.240" od all along, but will be 1.230" at the breech and tapered to 1" at the muzzle end , I don`t think it will move any. I`v slugged it and bore size is now at .450" - .457", that's good for a 45-70. Would like to make it octagonal, but with 4140 steel I don`t think my shaving way will work, have to look at maybe grinding it, :idea:, will keep you posted, Homebrew.357. 8)
Attachments
P1010953.JPG
Turning to 1" inch at the muzzle end, in tailstock.

Harold_V
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Re: Making a sharps barrel in my lathe.

Post by Harold_V » Tue Nov 18, 2014 4:33 am

redneckalbertan wrote: How straight does the barrell have to be?
That I can not answer.
How does one straighten it?
Ackley had an overhead press in which he'd place the barrel for straightening. It was hand operated, and circular in design. A large handwheel with a screw.
and How does one check straightness, by eye or with a dial indicator?
His method was visual. I expect it's actually quite precise, as it is done by looking through the bore. Any misalignment would be quite obvious. I do not know if there are other methods of inspection, or for straightening.

When completed, it's entirely possible the exterior of the barrel would not be concentric with the bore, due to movement while removing material. I do expect it would be minimal, however.

Harold
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Re: Making a sharps barrel in my lathe.

Post by Harold_V » Tue Nov 18, 2014 4:36 am

homebrew .357 wrote:Would like to make it octagonal, but with 4140 steel I don`t think my shaving way will work,
I'm of the opinion that it would work. Just keep the tool sharp, and take a reasonable depth of cut---perhaps a couple thou per pass? I fully expect that modest positive rake would be in your best interest, and that the tool should be fully withdrawn for the return.

Harold
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homebrew .357
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Re: Making a sharps barrel in my lathe.

Post by homebrew .357 » Wed Nov 19, 2014 1:42 am

Hi Harold, I`m thinking you could be right, my first barrel was 1045 steel and I only cut half a flat at a time and it was fairly hard stuff, so will give it a go, but will have to make up a eight holed register plate to fit on my rifling gismo. Have set up the barrel for taper turning the OD, muzzle at 1" dia and breech end 1.150", and the tulip bit that threads in receiver at 1.220". To stop the barrel centre area from chattering and acting like a wet noodle while machining , I wrapped a spring around the barrel and fixed to tool post, it has stoped most of the chatter and with a chip breaker side cutting tool seams to be working. 8) ,Homebrew.357.
Attachments
P1010957.JPG
Cutting the taper, spring to keep it steady.
P1010955.JPG
Muzzle end in tail stock that`s off centre.
P1010956.JPG
Breech end in centre and drive clamps.

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steamin10
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Re: Making a sharps barrel in my lathe.

Post by steamin10 » Wed Nov 19, 2014 9:14 am

Warning: If you have done any grinding of long bars, you will know that any heating, and just the act of stroking the bar can induce some major movements. Circular grinding is not as bad, as it tends to move everything in a band of the material. Not so with lengthwise finishing. That says coolant and light passes are the rule, and even moderate heating is to be avoided. Of course a nicely dressed and true wheel is needed for a smooth finish, without the chance of the bar (barrel) being able to bounce. Any movement will be clearly seen in the finish.

Just my thoughts, good luck.
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PeteH
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Re: Making a sharps barrel in my lathe.

Post by PeteH » Wed Nov 19, 2014 1:11 pm

Here's a decent photo of a barrel straightening press in use. IIRC, they would sight on a "crosshair" of some sort -- perhaps a line on the wall, or a piece of thread with a weight on it. They'd bend the barrel until it looked right. Probably was a LOT of "educated fingers" involved, knowing how much past the yield-point to push it.

I don't recall if they did this before or after rifling... obviously it'd be easier before, when all you had was the single bore surface to sight off of.

http://www.google.com/imgres?imgurl=htt ... =0&ndsp=23
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Re: Making a sharps barrel in my lathe.

Post by GeorgeGaskill » Wed Nov 19, 2014 4:12 pm

If you are going to use the lathe as a planer to cut the flats, I would try to do something to back up the barrel to reduce deflection while cutting. Maybe a strong back clamped to the back side since you don't have a good place to mount the clamps.

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Re: Making a sharps barrel in my lathe.

Post by Harold_V » Wed Nov 19, 2014 4:54 pm

GeorgeGaskill wrote:If you are going to use the lathe as a planer to cut the flats, I would try to do something to back up the barrel to reduce deflection while cutting. Maybe a strong back clamped to the back side since you don't have a good place to mount the clamps.
I'd certainly a agree with that idea. I'd also entertain the idea of taking uniform cuts, alternately, on all sides, as removing all of the material from one flat, to full depth, is sure to result in movement of the barrel. By taking uniform cuts on all sides, slowly achieving full depth, movement will be minimized, or even eliminated.

The movement of which I speak is due to internal stresses of the material----which are ever present, even in hot rolled materials. Relieve them unevenly and movement should be expected. Equally for all surfaces? Not so much.

Harold
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