For those of us with no knowledge in the area and possessing only a propane torch, is there a way to harden and temper small things like a 4" blade handmade knife?
A method that will work but eats a lot of propane to get to the heat needed is as follows. You will need a few bricks to make a small enclosure to help trap some heat , just a simple box closed on 5 sides leaving one side open to hold your blade with vise grips and torch into.
Heat the blade red hot until a magnet wont stick to it and quench in a couple qts motor oil or tranny fluid , have a cover ready in case it flashes off.
Clean and polish blade for next step.
In good light heat the back of blade evenly running flame back and forththe length of backbone and watch for colors and when you see yellowish tan , straw color at the cutting edge quench and swirl blade in oil till cool. The color you are looking for is more of a patina look than a heat color of the first operation.
Like Frank said. One thing though, be aware that all steels are not heat-treatable. I thought I'd mention this in case you tried it, and had no results.
There's about as many types of steels and heat treat methods as there are frekels on Howdy Doody. ;D
For what its worth, the current copy of the Backwoodsman magazine has an article in it on steels used for knives and what the ratings are, ie, W2, o17, 1095, etc and it also has an article on making a file knife and the tempering process for that, thats the Nov/Dec 2008 issue, you may want to check your local library and see if they have a copy of "The Complete Bladesmith" best book I have read on knifemaking, hope this helps, LM
I would normalise the blade before hardening and tempering. Heat it until it is nonmagnetic then let it cool until you can handel it with your bare hands. Then harden and temper. You can also temper it in the oven on your stove set the temp. to about 500 deg. place the blade in the middle of the oven and watch it until it is the color you want. Then quinch in water.
Thanks for all the advice. I'll be trying most of them out this winter. A guy sent me some hammered steel to grind some knives out of, if I could. I have no idea as to the type of steel so this will be an experiment for me. I ground them to various knife-like configurations on a strip sander so will be smoothing them out and trying my hand at tempering/hardening. I guess if you get a good edge that lasts a while it is the first indication that you did something right. Anyway, I have several to play with when the weather is too nasty to do anything outside.