Metal hardening

[Ray C]

For precision parts of O1 tool steel, it's best to fully normalize the metal before working on it. Also, make the part slightly oversized so after final heat treating, you can grind the part to final size. That is the recommended procedure for precision parts made of tool steel. To normalize the metal, bring it up to 1600 F and let it gradually cool in an open oven until room temperature. Once you do this, the metal will be very soft and cut like butter using normal HSS or carbide.

Yes, tool steels are a little expensive -especially if you purchase first-rate material with certifications. I usually settle for the odds&ends pieces that most suppliers sell at a slightly lower price.


Ray

Yes...both parts I need to make are small...just a hammer and trigger. The Metal Supermarket here has a bits and pieces section as well. I was in a bit of a hurry by the time I got there, so I just grabbed a bar they had on the shelf...walked up to pay for it....choked a bit....and hurried along to my next stop.

One thing I should ask before sacrificing another perfectly good end mill to the gods of inexperience. What end mill material should I be using on this stuff ? Should I be looking for a pure carbide one, or will the HSS or cobalt ones I already have do the job ?

 

[george wilson]

DO in any event,take my advice: STOMP the holes TIGHT with fine steel wool with a flat ended punch to prevent holes from cracking through to the nearest edge. Gun parts tend to have holes near edges.

Toolmakers used to stuff clay into holes,but then the insides of holes don't harden well. Now they use steel wool,and the holes will harden well.

 

[DMS]

The stuff ships in a soft state. It cuts really well, so you can do it with HSS or carbide, doesn't matter. I find that if the tools are not sharp, it turns up quite a bur on the top surface, but nothing a little filing won't fix. I have never normalized before machining, but then, most of my parts are small. The larger ones are non-mechanical parts (I have been making woodworking tools for my GF, who is a woodworker), so I was not that concerned with finishing to exact size.

The other thing to consider (depending on your machines) is that the stuff can be machined in a hardened and tempered state with carbide. So, you can machine to rough size, harden, temper, then take a light finish pass for final dimensions. In a pinch, a piece of wet-dry sandpaper placed on a flat plate will also give you a decent flat surface.

 

[cdhknives]

One of the reasons O1 is so expensive is that it is held to tighter tolerances than most other steels. It should be reliably annealed and precision ground.

Knifemakers search all over for non-PG O1 stock.

 

[benmychree]

Another source of 0-1 cheaper than most mentioned here is McMaster Carr; you can order online, and pay via debit card; the size mentioned was 1/4" X 1" X 36" they list it at $37.04. they have fairly fast shipping.

 

[gtboomer]

Try KBC Tools, http://www.kbctools.com/can/main.cfm they do mail order and have a branch in British Columbia. Metal Supermarket is way to expensive.

Good luck with your project.

 

[george wilson]

Bernie: I am happily using the salt you generously sent me!! It doesn't just fall off of the food I'm shaking it onto. Thanks again. Now I can heat up french fries good and hot and quench them in my mouth!!

 

[gi_984]

To George Wilson: Great tip on stuffing the holes with steel wool. What modern book or other reference would you recommend for heat treating?

Thanks,
Chris

 

[12bolts]

.... Take a flat nosed punch and stuff any holes in your parts with fine steel wool to stop the risk of the parts cracking where there are holes. The steel wool makes the parts act like they have no holes. .....

George, What would you recommend for retaining the steel wool in a through hole? I am shortly going to be going this way.

Cheers Phil

 

[KevinD]

There's another alternative, super quench. It's a solution of salt, dawn dish detergent and surfactant like Jet Dry. Super quench was developed as a safer alternative to an older technique using a saturated lye solution for a quench. It will allow one to forge/grind a cold chisel out of mild steel and then use it to cut through it's parent stock. I've never tried it as a machine tool cutter, that would be interesting. I'll report back if I get my roundtoits in order.
http://magichammer.freeservers.com/robb_gunter.htm
I'd also like to offer a word of safety about quenching steels. It's possible that quenching a steel too fast can cause it to explode in the quench bucket. You should be sure to only quench air hardening steel in still/room temperature air, never oil or water. Seems there's also a bit of dyslexia going on with terminology; anneal is to slowly cool the steel in vermiculite or ash (since we aren't likely to have heat treating ovens); normalize is to cool the steel in still/room temp air. Normalizing steel ends up harder than annealed, which is the softest state and the state most likely to be successfully machined. There has been some excellent information in this thread.
Happy New Year to all.


EDITED BY GEORGE WILSON: I have actually tried super quench. It only gave a SLIGHT increase in hardness over regular mild steel. Certainly nowhere near enough to make safe triggers and hammers from. This is a major safety issue when it comes to making gun parts. Please do not post folk lore that you do not have direct experience with. Someone could get shot by a worn trigger sear that let the gun go off by itself,or go off full auto in some cases.