Hardening Blades

[p. gannon]

I am looking for some general rule information regarding good hardening of a knife blade made from an older American made file without exact knowledge of carbon content.

1. Should the blade be properly annealed prior to hardening?

2.   What is the general hardening temp that should be reached? 

3.   Should the blade be quenched in distilled water, oil, or brine?

4.   What temperature should the quenching solution be?

5.   Is a lead bath appropriate for drawing?

Thanks,
Paul

[LRB]

  If you forged it, bring to around 1500°, soak for a few minutes if possible. Let cool to room temp. Then heat just short of non-magnetic. Non-magnetic is 1414°. You really want no more than 1300°. let cool to room temp. Do this three times. Then take it back up around 1475°, to 1500° quench in thin oil heated to 130°. Temper in your kitchen oven at 425°, to 450° for two, two hour heats. Use an oven thermometer. No, a lead bath is too hot for a knife temper. It will make a good spring however.
 1500°, to most eyes, is a bright red-orange in dimlight. If you have no heat control for the triple thermocycle, then bring it just to the point where a magnet no longer attracts, and let cool. That should be close enough to work. Peanut oil, canola oil, or ATF will get you by. Not perfect, but will work.

[Dphariss]

When you quench a knife it is very easy to warp the blade. I like to quench by plunging straight down vertically. No stirring for the first 2-3 seconds.
You use SAE 10 motor oil thinned with diesel fuel or Marvels Mystery oil. You heat by heating a steel bar and putting it in the oil. May take quite a bit of oil of oil for a long knife.
Anneal to a "straw" color, the back where it is thickest can be heated to blue or much darker straw with a torch but do not let the blue run down close to the cutting edge or point.  Heating the back in this manner makes tougher blade. You can protect the cutting edge and point by putting the point/cutting edge in water.
I generally anneal for final shaping so annealing prior to heat treat is superfluous .
Dan

[JCKelly]

About 1985 Muzzle Blasts was kind enough to publish an article I wrote, more or less "New Knives from Old Files".
I just upgraded it a bit & sent the 7 page pdf to Gannon.

I do not know how to put such a large thing on this site.

Anyone wants a copy, email me at jkellymetal@gmail.com

[Chuck Burrows]

Mr Kelly if you email it to me at chuck@wrtcleather.com I will see that it gets posted..........