Heat treating with a torch?

A few years back I filed a blade out of an old cicrular mill saw that was laying in Grandma's barn. I was able to put a good temper on it with an oxy-a rig.
Working from the spine I heated the whole length to an even cherry red testing frequently with a magnet until it was no loger magnetic. A few more seconds of heat and i immersed it in cooking oil of all things.(There was a buch left over from the Fry-Daddy I thought a shame to waste.) I plunged it in point first and escaped with a little bit of warping. After cleaning it up with sandpaper then some Dawn (de-greases the blade)I put it edge down in a pan of water and heated the spine blue. I now had an incredibly hard edge and soft back (easily cut with a file). I polished it up again and then played the flame along the spine until a nice straw color came within a few hundreths from the edge. I removed it from the heat for a few and plunged point down and edge up into the oil again. Then I degreased it again and stuck it in the oven for at 425 for about half an hour and buried it in some ash to cool.
This is a lot less than scientific, I'm a Boastswain's Mate after all and prone to fixing things with a large heavy object, but i have used this knife for many years. It has a little warp, but the steel is probably only 5/32 on the spine so i imagine it warps a lot easier than a thick blade. Or, I could be talking out of my ---.
Good luck whatever you try, but experiment, it is fun and I think you will find it gratifying.
Sar
 
Sar, if this was a first effort I'd say you had pretty good luck. But I'm not all that surprised. Most Bosuns I knew could make or fix just about any damned thing.
 
An shipo mate of mine from a buoy tender once said if it didn't involve tieing a line to it a BM couldn't do it. I'm going to forward him your reply. Oh and thank you for the welcome
Sar
 
Well, the BMs I served with 50 years ago could do and did just about everything to keep that tin can going. And when we lost a man overboard in a storm it was a BM who tied a line around himself and volunteered to go after the lost man. The Captain forbid the action. We made one pass, trying to save the man, rolled 70+ degrees and I guess the Captain figured it was better to save 300 than one and steamed away, leaving the man to his fate.
 
Did that really happen Uncle Bill!!?? Very interesting! Also thank you Rob and welcome to the Cantina!!!:)
 
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