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Dealing with warps post HT is something every knife maker needs to master. Its very easy. If a blade is already hard (tempered or not), and develops a warp, use the 3 point clamp method. It works....every time. You may need to do it a 2nd time if the warp didn't straighten, or if it was over-corrected, but eventually you will get it straight, and doing it multiple times is not going to drop your HRC.
Find something like a piece of scrap steel, about the length of your blade.
Find a fulcrum point....I like to use a brass pin...nails can scratch your finish...brass not so much
Find 2 clamps that can be put into the oven.
It's pretty self explanatory, but clamp the scrap steel on your blade near the back of the handle, on the side of the bend that is convex. Place the brass pin (fulcrum point) in the middle of the bent area between the blade and scrap steel. Use your 2nd clamp near the tip, and crank down until the bend has been over-corrected by the same amount in the opposite direction. Place into oven 400F for one hour. After the hour, I take it out and set it in the sink and spray with water (steam!). Not necessary to spray with water, but it makes the cool down (did it work?) faster...and may be of some benefit. Usually it takes me just once. But I did have a 52100 chef give me fits recently....had to run it 3 times.
I've heard some say they clamp the piece dead straight and put it into the oven. I don't see how that can possibly work. The result would be a bend that is half way between dead straight and what it was when you started. (If it was bent 5?, the result would be a bend in the same direction 2.5?...roughly). I have ALWAYS had to over-correct a warp to make it straight (once the blade is hardened and/or tempered as well).
Yeah...Peter's does use a torch to straighten. While it works, I don't like the idea of a soft spot on the spine of my knives. AT ALL. Not really a huge deal...but not the best way. But they have to figure a way to make it economical for them.
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