Question on Tecnique ??

[Bill Gruby]

I very seldom venture into this domain. No I am not against guns. Here goes.

I was looking over a set of prints for the Sharps 1874. On the receiver there is a thru hole top to bottom. It measures 1.499" X .772" and travels for some 2.475" all the way thru. There is a radius on each corner traveling the length of the hole. The radius is a nominal .015". Without divulging any of your trade secrets, how do you get this type of radius.

"Billy G"

 

[Bill Gruby]

22 views, no answers. :lmao::lmao: One more thing, this is the hole the "Breechblock" raises and lowers in. I am assuming this must be held close to spec.

"Billy G"

 

[Codered741]

Well I'll take a stab at it. Im not a gunsmith, just a lover of guns, and not an expert on the sharps rifle.

But purely as a theoretical question of how to make a square hole with a radius in the corners...

I would say for a production line, the easiest and most repeatable way would be a broach, custom made with the radius in the corners. Making one at home, I would either drill the corners with the correct size drill, then mill out the excess material, or go old school and break out the rat tails.

There, maybe that will prompt someone into correcting me and give you the right answer. :lmao:

-Cody

 

[Bobby Bailey]

Bill and Cody, A broach would have been the way to go. Though on the Sharps unfinished receivers generally sold you can clean them up with a file.
Bobby

 

[Tom Griffin]

I cut the rectangular holes in the receiver of my Steven's with a slotting tool that uses a carbide insert. The tool is simply held in a collet and used like a manual shaper. Since there is no clapper, lots of oil is required. I'm pretty sure you can get inserts with a .015" radius.

Tom

 

[Alphawolf45]

I drill, mill and then file the mortise square and sharp cornered ..Follow with a pointed round file to round out the corners and then polish with an abrasive stone that I grind to 30 degree angle so it settles into the corner without touching the sides.. Use good light and magnification. What you need to do is radius the corners well enough to eliminate any scratches that follow the mortise.. . .015 radius isn't much and I usually end up with bit less but polished slick...And I usually make receivers at least .020 to .050 thicker than originals... I'm presently building a Highwall in .45-70 for BPCR silhouette competition . Will be making double set triggers for it next week. Picture shows the filing fixture that I built for this project and an extra roughed out Highwall receiver that I just cut out for grins and giggles, probably wont ever use it.