Still working on the drawings. Have most of them finished, doing custom screws now. Need those for the existing holes in the receiver which are oddball threads, close to SAE but a tad looser. Also researching casting as I'm thinking of casting the lever parts, trigger and breech block parts from silicon bronze. Should be plenty strong since this is a black powder gun. Probably try lost wax investment casting as I've done lost foam aluminum casting in the past.
Most of those bits were case hardened steel, not so much for strength but for wear. Probably not an issue making them in bronze since you wont be going into battle with it daily but I'd still be careful Anyway welcome to the forum and sounds like a cool project.
Photos or it didn't happen! Welcome aboard! If you've never poured silicon bronze, you are going to love it. It's a wonderful metal to work with.
Another option would be gunmetal or red brass as it's sometimes known. Used to be used for all sorts of heavy ordnance. Just Need to find a supplier for it. Gun looks like this:
I have used a fair bit of red brass / LG2 leaded gunmetal and it's not that hard: 70 Brinell versus 126 for 1018 mild steel. It's preferred for ease of machining, pressure tightness and corrosion resistance but the "gunmetal" name is a bit of a misnomer. Aluminium bronze is by far and away the strongest of the copper alloys with C954 aluminium bronze having a hardness of 170 Brinell and close to three times the tensile strength of leaded gunmetal bronze (1.33 times that of 1018 mild steel). Bronze is more noble or cathodic than steel so anything like steel parts in contact with bronze is going to preferentially corrode, like springs for example.
Imagine building something like this before the days of electricity! Paul probably has a Tormach and a full machine shop too! It's going to be cool to see something like this done here.
Civil war vintage is correct, circa 1864. Perhaps my question to all would be what would be the best material to use for the castings? The lever and some other small parts are not highly stressed, only the breech block. Black powder only produces pressures on the neighborhood of 25k psi, much lower than smokeless. Had an offer for some manganese bronze. Better or worse than silicon bronze or aluminum bronze? No steel suggestions to cast as I don't have the facilities for that, just the aluminium and brass region. No Tomach here, just a small shop with a 7x12 lathe and mini mill
I was thinking aluminum bronze might be a good choice, @Tobho Mott would have better insight to its properties than I would though...
Jeff will tell ya it makes a hell of a good axe! Keep in mind, sil bronze doesn't machine the best as it can be gummy because of the high copper content (~94%) With that said, I took a few passes across a sil bronze ingot a couple of nights ago. Not too shabby if ya ask me. Yeah, I took 30seconds with it on the polishing wheel.
Machinability of the castings is going to be a significant issue if you're using machines at the smaller end of the scale and may rule out the harder and tougher to machine copper alloys. One option would be to machine wax versions of the parts you need and send them out to be investment cast in steel at a commercial foundry. I recall some guy on another forum making frames and slides for M1911 pistols in alloy steel that were investment cast to near net shape with minimal machining needed. Another option is case hardening using CO2 gas and a carbon pack in a furnace. This lets you make all your parts from mild steel which is relatively easy to machine and then give them a glass hard surface similar to cyanide case hardening but without all the toxic chemicals. Quite deep case hardening can be done with this method.
I never invested in a hardness testing kit or anything to get actual numbers for the handful of C954 aluminum bronze axes I've made, but I can say that their edges hold up fine for chopping hardwood logs once I have peened them to work harden the bronze. And not so fine when I miss with a swing and hit a rock. I have read it can be hardened by heat treatment as well, unusual for an alloy of copper, but apparently true. I haven't tried that yet. It turns into foamy dross easily; care should be taken to minimize turbulence in the gating system and mold cavity. So it's not nearly as friendly and clean to melt and pour as, say, silicon bronze... but then what is, really? Appearance-wise, it is quite yellow, not much red to it at all compared with other bronzes I've seen in person. Shines up to a nice golden colour. I don't know how helpful that actually is, looks like a cool project though. Welcome to the forum, good luck with it and keep posting your progress! Jeff
I usually only see these kind of builds on the Home Gunsmithing forum...but yeah...looking forward to it too. Mentioning doing it sans electricity reminded me I've not watched this in a year or so...good if you have an hour to kill. There's casting too. Al
