Firearm Building
- Thread starter SmeeAgain
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tark
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And I invented some new cuss words... which I wont repeat here. Mods would harpoon me. Bench top machines are wonderful, within their limitations. Most of the machining on my 45-70 rifle was done at work using Les' milling machines. All of the machining on my 30-06 was done in my basement, on my Smithy machine, an hour here and an hour there after work. It took me seven years to complete it. Wish I could stand for more than thirty seconds without excruciating pain in my back. I want to try another project but...
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SmeeAgain
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One of the greatest experiences I've had came from a YouTube video on how to rifle a barrel.
I had to try it! I took a square piece of steel stock, milled it into an octagon, then bored it on my HFT lathe.
I then hand made a "button" and pushed it through.
It worked! Looks beautiful too.
On my next build I'll do the same process.
So far I've always used rifled blanks & modified then as needed making everything else from scratch.
The old days of cheating are gone. Soon I'll be able to say I made everything but the steel.
I had to try it! I took a square piece of steel stock, milled it into an octagon, then bored it on my HFT lathe.
I then hand made a "button" and pushed it through.
It worked! Looks beautiful too.
On my next build I'll do the same process.
So far I've always used rifled blanks & modified then as needed making everything else from scratch.
The old days of cheating are gone. Soon I'll be able to say I made everything but the steel.
BigBlue 94
Member
Ive seen how rifling was done in the early days. Does the button control the twist rate or something else?
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SmeeAgain
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- Feb 8, 2022
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Yes, the button determines the twist rate. It cuts the grooves as it is pushed through the bore. Much like a broach but spins as it travels.
It's crude but does an amazing job for what it is.
In my test, I didn't bore it for any particular caliber or twist rate. I just used a 1/4" drill then made a suitable button with an unknown twist. I was quite impressed with the result.
The only rifling machine I spent any time around was a modified Rock Island Arsenal machine that was made to rifle .50 BMG barrels.It was modified to work with buttons or broaches.The button was turned by the movement of the ram.It takes a lot of force to pull a button and don't believe the button could turn itself.Our barrel men never tried.
PRD1
Member
I've made around 1,000 cut-rifled barrels on a Pratt & Whitney #1 sine bar rifling machine, and can tell you that cut rifling is by far the most versatile and economical means of rifling a barrel. A rifling machine can be as simple as the early gunsmith's rifling bench, with a fixed-pitch guide made from a wooden cylinder - there are several books in which you can find instructions for laying-out and finishing the guide cylinder: 'The Muzzle-loading Caplock Rifle' being a good one. There are also sources for designs of sine bar machines, which, though more complex, are also much more versatile, being easily adjusted for any pitch within their mechanical range.
Button rifling requires the ability to lay-out and grind complex geometries in the button, most commonly made of Tungsten carbide or similar modern alloys - the button must be MUCH harder than the barrel material, and perfectly smooth. The barrel is also commonly lubricated for passage of the button. The button must be designed for the caliber and rifling pitch desired in the finished barrel, and must be optimized in dimension for the specific state of the material to be rifled, since passage of the button swages, or displaces the barrel material, deforming it permanently, and changes in the hardness of the material from barrel-to-barrel, or even within the same blank, can cause variations in the pitch and internal dimensions of the finished barrel. The pitch of the button is what determines the final pitch of the barrel, and the button can be either driven or pulled through the blank, but attaching it to the driving rod cannot control the motion of the button in the bore: the forces on the button are far too great (ca. 200 KPSI) to respond to any additional torque from the driving rod. If you doubt this, clamp one end of a barrel-length drill rod of the largest diameter which could be freely passed through the proposed blank bore in your bench vise, and clamp a vice-grip to the free end: you can easily rotate the pliers through several degrees without much difficulty, and the button in its passage through the bore will not be influenced by the force possible to impose on it through the driving (or pulling) rod. A broach, being a cutting tool of significant length, having teeth of progressively greater height, even though designed with the same pitch as desired in the finished barrel, must be lead through the bore mechanically in the same way that a single-point rifling cutter is, since it cannot drive itself to rotate, and would simply enlarge the bore in line with the broach's teeth as it passed through the bore, unless it were rotated at the pitch designed into it.
PRD1 - mhb - MIke
Button rifling requires the ability to lay-out and grind complex geometries in the button, most commonly made of Tungsten carbide or similar modern alloys - the button must be MUCH harder than the barrel material, and perfectly smooth. The barrel is also commonly lubricated for passage of the button. The button must be designed for the caliber and rifling pitch desired in the finished barrel, and must be optimized in dimension for the specific state of the material to be rifled, since passage of the button swages, or displaces the barrel material, deforming it permanently, and changes in the hardness of the material from barrel-to-barrel, or even within the same blank, can cause variations in the pitch and internal dimensions of the finished barrel. The pitch of the button is what determines the final pitch of the barrel, and the button can be either driven or pulled through the blank, but attaching it to the driving rod cannot control the motion of the button in the bore: the forces on the button are far too great (ca. 200 KPSI) to respond to any additional torque from the driving rod. If you doubt this, clamp one end of a barrel-length drill rod of the largest diameter which could be freely passed through the proposed blank bore in your bench vise, and clamp a vice-grip to the free end: you can easily rotate the pliers through several degrees without much difficulty, and the button in its passage through the bore will not be influenced by the force possible to impose on it through the driving (or pulling) rod. A broach, being a cutting tool of significant length, having teeth of progressively greater height, even though designed with the same pitch as desired in the finished barrel, must be lead through the bore mechanically in the same way that a single-point rifling cutter is, since it cannot drive itself to rotate, and would simply enlarge the bore in line with the broach's teeth as it passed through the bore, unless it were rotated at the pitch designed into it.
PRD1 - mhb - MIke
BigBlue 94
Member
Thats the way ive seen it done. On video of course. Ive been to a number of machine shops, but nothing related to barrel making.
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