Ok here we go

[shadow]

As I was looking at my pistion for my B3, not the greatest craftsmanship I've seen. I was thinking , this would be a good first project for the lathe.Am working on blueprint stage, abunch of work before I even fire up the lathe.Question: what grade metal,type etc is required. Thanks Ed

[DanoInTx]

I've never had a B3 apart, but it doesn't sound like a terribly hard job.  What I think could be hard is that the material that you use would have to be hardened, at least in the sear area...this is just my opinion.  So you have the choice of trying to machine hardened steel, or heat treating soft machinable steel.  Most of my metal experience is with sheet metal, aluminum specifically and it's been awhile, but what I do remember is huge kilns and oil quenching baths.  I don't want to stop your project, but I would do some research to at least find out what material will work here, you don't want a piston that you can't use, or worse a piston with a sear that is uncapable of holding the spring load.  The key phrase here I think is "be safe".  Man, what ever happened to the good old days when guys with lathes were just happy making muzzle brakes and Crosman bolt handles?

Dan

[shadow]

Thanks for the reply Dan and yes it's going to be a project. I've been in touch with my brotherinlaw, he works for GM in the machining dept.. He's checking on some info for me and he will hook me up with the materials I need to fab a high quality peice as he puts it.It's nice having family with connections:).Safty first, Ed

[Gene_SC]

Hey Ed

Sounds like a great project. I am sure some one will chim in with more info.. :)

Gene

You can use a carbon steel and then you can do the hardening yourself, you would oil harden the steel and then temper it to the correct temper. To harden carbon steel you heat it red hot and quench it in a bath of old motor oil and then polish it up and then heat it in your oven to the correct temperature for the temper you desire. It’s like when I was in high school and we made a chisel you heated red hot quenched it in oil this makes the steel VERY hard but brittle, you have to temper the steel to make it tough. To do this you temper the steel by reheating it to a set hardness and this is done by the color of the steel as it heats up, a straw color would be for a chisel edge or a knife edge. Heating to a blue color would be like for the end of a chisel that is struck with a hammer, not hard enough to chip or shatter when hit but not soft enough to fold over with use.

Carbon steel is a little harder to machine because it is quite tough to begin with but it’s not a big problem. The main thing with any steel you are going to harden is that it is going to grow a very small amount when heat treated, on something like a compression piston I would not worry about the growth but if you were making a pin or a shaft it would make the part have to be ground to the correct size after heat treating.  Another option is to use plain cold rolled steel and take it to a heat treating company and have it case hardened, they  can harden the surface to .080 to .125 deep which would be adequate  for the sear surface on a compression piston

[shadow]

Thanks guys, I can always depend on GOOD info from fellow members. I'll keep all updated on progress, If you see a small mushroom cloud from the S.D. area there will be a small delay in my report he he . Ed

Rich,
That's the first time I've come across anyone who understood tempering steel by colour, since I served my apprenticeship in the early 60s. On the drilling rigs, the guys (even the mechanics) thought it was black magic, especially as it was being done by an electrician!!

[IJL]

I thought everyone tempered steel by the colour. What other way is there without very accurate temperature control??

Ian

Re: tool steel
A good source of small quanties of tool steel is your local bolt supplier.
Just get a Grade bolt large enough to machine what you need.Grade 5 or grade 8 is Fairly hard but they are machinable.
Should be reasonable and you dont have to buy a long bar for a 1 inch piston.
alabamaed36046

Check your local steel warehouse they always have a shorts or cut off bin to buy stuff out of.
I get most of my aluminum and brass this way, even the stainless to make QB78 bolts out of.

They normally sell it by the pound, I pay 1.74 a pound for cut off brass and aluminum.

[shadow]

Ditto on what Rich said, that's where I got my metal for my B3 pistion project, coming along slow but steady. Wanna do it right the first time. Ed