rifling button pusher

Milwaukee 3/8" x 24" HSS Installer drill bit:

You'd have to determine how far in the chucking end was annealed. jsw

If the bar can be 0.35" diameter, you're looking at less than 0.1 ^2 in. of area. Yikes. You need 100 ksi compressive yield strength in the bar to handle the full five tons.

HSS is no stronger than many high-strength alloys. Pre-hardened, ground drill rod is available.

Another possibility is the bar stock from Timken and others, intended for making roller bearings. That stuff runs upward of 180 ksi tensile. In most steels, compressive strength is close to, and directly related to, tensile strength. And tensile specs are easier to find than compression-strength specs.

Music wire in these dimensions is not nearly as strong as the thinner types.

Good luck!

Hi,

Would a solid carbide bar work as a pusher?

This is why pulling buttons is preferred of course.

Didn't you say you were doing the gun drilling on a Hardinge CNC? If so, don't they have a max of 12" in Z axis travel? How's that all going to work out?

G'luck,

Any idea where to order the timken stuff?

What about the carbide listed in the next post?

Karl

You need a small steel supplier or a steel service center that will sell you a little piece. They don't want to, but sometimes they're sympathetic.

If it were me, I'd look into Timken's list of suppliers:

...and get on the phone with them. Tell them frankly that you need one piece. They may know of a supplier who will do it for you.

Or you could become a manufacturing magazine editor and ask for a sample. d8-)

Timken bearing steel is the high-end solution. Really, 0-1 is more than enough. It's typically delivered in one of three conditions: annealed, as-rolled, and hardened. As-rolled is Rc 50. Its compressive yield strength is 196,000 psi -- 'way more than you need.

That's probably the easiest one to get, because small steel suppliers, and even online hobby suppliers and *maybe* Brownell's, deal in onesies and twosies of that material.

Crack!...goes an expensive piece of carbide. It's not tough enough for futzing around with a small-shop press.

Again, good luck. You shouldn't have trouble finding a piece of steel that's strong enough, although ordinary mild steel might turn to mush under that much compression. Go for a good, common alloy steel, or maybe a hardened piece of 1070 or1090 carbon steel, and you should be able to do it. At that small diameter, even cold-rolled high-carbon should do it. Cold-rolling hardens small diameters much more than larger ones.

(I always thought they pulled, rather than pushed, rifling buttons, but maybe that's just the gun manufacturers.)

Thanks for the carbide lead. A push button was in my (super cheapo) price range.

I'm going to modify a turret plate with a 1.375 square by real long gundrill tool holder. Drill 12", back up and stop. Loosen holder, slide ahead, restart drilling. I'd use a manual lathe but the hardinge has a nice flood coolant setup and complete enclosure.

Karl

Thanks, not bad advice for a flaming liberal from KCB.

Push type buttons are cheaper, fits my lifestyle. Also, from what I've read, pull type actually fail more easily. The pull rod breaks right where the threads end.

Karl

Yeah, I could see that.

I guess I told about the rifling tool we used in my old shop to make a muzzleloader pistol barrel. It was an adaption of the tools that Pennsylvania rifle builders used over 200 years ago. We stacked a few pieces of hacksaw blade side-by-side into a tool we made from drill rod, with one slot in the side to hold the blades. We shimmed under the blades to adjust cut depth, progressively through multiple strokes.

For a final finishing pass, we ground a lathe bit to fit in the slot and cut a couple of tenths to make the grooves flat and smooth.

The tool for controlling twist was a 3/4" piece of square bar that we clamped at one end in a monster vise, put a big pipe wrench on the other end, and twisted. This was pinned to the cutting tool and drawn though a piece of plate with a square hole in it. Indexed four times, we got a four-groove barrel.

My partner in that job shop had apprenticed to an antique gunsmith (both the guns and the smith were antiques) in New Hope, PA. He learned a lot of tricks and made several rifles and a bunch of horse pistols from scratch.

Ahhh, very clever that.

I would think your push bar problem is less about compression and more about bowing. An uneven force will c*ck the button off center for a bad result...as far as I understand it.

I've heard of using hydraulic force to push a button through a (threaded) barrel. I wonder if some type of a grease gun would have enough pressure?

Will look forward to updates on your progress.

I am still hoping to make a reproduction rifled barrel for my .177 air pistol some day.

Would a Grade 8 bolt shank (or a stack of them) be strong enough?

jsw

Supposedly their tensile yield strength is 130 ksi. Compressive strength should be similar.

It's no a lot of margin, but it theoretically should be OK. I'd worry about a stack scratching up the bore.

It's so constrained by the bore that there would be no significant bowing.

I'd think that it's important for the mating faces to match well and to be most of the bore diameter.

A piston rod salvaged from an automotive type gas spring would probably work fine.

Probably. Almost all of those are made from 1070, not an alloy, but they're fairly hard and should be strong enough.

Certainly once it's well in -- but if those things work the way I think they do, getting it started would be critical.

Of course, I'm just extrapolating from the term -- I haven't even hunted up a YouTube video of the process.

How about 3 grains of Bullseye?

That's a good point. Maybe a guide wold be needed. Also, maybe that's a good reason for pulling rather than pushing. That's the case with very long (often over 12 feet), thin broaches. Beyond a certain length and minimum diameter, they're usually pulled.

But they have guide bushings if they're pushed. With the skinny push rod talked about here, you'd certainly need some kind of help at the beginning of the push.

Karl - how have you calculated the neccessary force? 11000 lbs sounds hopefully hi.

Hul

Karl Townsend wrote:

I am a frugal person so my suggestion would be to go to your auto salvage y ard and if you can find it, get a torsion bar from a Nissan Truck. Second choice would be an axle shaft. Both will require reducing the diameter usi ng a carbide bit. But if you do use steel from a auto wrecking yard, try t o get steel that as close as possible to the diameter you want. Not only f or less machinging , but I am not sure how deep the heat treatment goes on axles and torsion bars.

Dan