Which alloys for machining

Can someone offer some guidance on choosing alloys for different uses that must be machined? I'm cutting some acme thread components soon for a stop on the Powermatic mortiser project. What alloy should I use for these threads? It's not a high stress project. Second is a general steel for gunsmithing. Anyone know what would be appropriate for picatinny rails? Might make a replica of a specific historic flash suppressor for an M1 too, guesses on alloys for that?

Obviously I'm a noob at this, but having fun.

It might be overkill but you could use 4140 for both parts. It's strong machines well and will take bluing. It's what the barrel of your M1 is probably made from.

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Originally Posted by Jerry Bruette

It might be overkill but you could use 4140 for both parts. It's strong machines well and will take bluing. It's what the barrel of your M1 is probably made from.

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Thanks Jerry, appreciate the info. I was also curious what barrels were, so good to know!

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Originally Posted by Steve Rozmiarek

Can someone offer some guidance on choosing alloys for different uses that must be machined? I'm cutting some acme thread components soon for a stop on the Powermatic mortiser project. What alloy should I use for these threads? It's not a high stress project. Second is a general steel for gunsmithing. Anyone know what would be appropriate for picatinny rails? Might make a replica of a specific historic flash suppressor for an M1 too, guesses on alloys for that?

Obviously I'm a noob at this, but having fun.

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I don't know about the alloys for your application, but Online Metals has a guide of the properties of different materials and alloys which might be good for comparison:
https://www.onlinemetals.com/en/product-guide

I purchase steel, plastics, aluminum, and brass from them and have always been satisfied.
For the gunsmithing I suspect there is a forum or two about that. Or call your favorite gunsmith.
Perhaps there is a machining forum also.

JKJ

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Originally Posted by Steve Rozmiarek

Thanks Jerry, appreciate the info. I was also curious what barrels were, so good to know!

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I think most pic rails are made from aluminum, then anodized.

Steve, Jerry is correct about Picatinny rails being made out of aluminum and then anodized. A few months ago I had a friend who has an early 1900's hunting rifle that has a claw mount. He wanted to be able to use a pic rail to mount a scope. Originally I thought about making both the rail and the two claw connections but then realized that there are dozens of companies that make pic rails. You can buy them, like from Amazon, for around $10 a pair so it wasn't worth my time and effort to make the rail, just the other two pieces.

You guys are right about the picatinny rails. I typed faster than I thought. What I was thinking was the scope mount for the picatinny rail. What I'm thinking of is a thin, low profile mount steel mount for an ACOG. The mount on mine is a big clunky hunk of aluminum with huge knobs on it. Maybe its a dumb idea, way down the priority list anyhow.

I'd look to a 12L14 steel (McMaster Carr) for that acme thread. It's alloyed with lead to make it easy machining which I think you'll find is better especially on a small lathe. But I don't think it is weldable, if that is important to you.

Not familiar with what you are going to be making but you can buy acme threaded rod if that would be beneficial and faster. If the correct pitch is available.

Looks interesting Leigh, I'll try some! Ronald, I'm modifying a Powermatic 10 mortiser. Previous owner added an air cylinder and took off some of the foot pedal components. As a Franken-mortiser, it's fair game in my book to make a depth stop system by modification of the existing parts of a stop into something practical. I bought a couple versions of appropriate acme nuts and couplers that fit the screws I have, some fit, some don't. Not very good quality control, or my old screws are out of spec. Probably the latter I'm guessing.