Straightening after HT question...

C

CDH

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Jun 8, 2007
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So I got a thin (1/16" stock) ATS34 boning blade back from the heat treaters...(name withheld for now) and it was pretty crooked. It is 11" overall and when laid on a flat plate it bowed up over a tenth of an inch in the middle.

I put 3 pieces of brass rod in the vise and began working the kinks out. I got it visibly straight after about a half hour of working it. It isn't perfect, but you have to really study it to see the warp. It'll do.

Now, do I need to temper it again to get the stresses from the straightening process out? Is it likely to shift over time or will it stay straight? It did get a cryo cycle in the HT (at least I paid for one and it was on the receipt) so it shouldn't have much retained austentite...
 
Never attempt to straighten at less than 400 F. If you temper clamp between two flat plates .Temper at at least 400 F and up to the original tempering temperature.
 
mete said:
Never attempt to straighten at less than 400 F. If you temper clamp between two flat plates .Temper at at least 400 F and up to the original tempering temperature.
Click to expand...

That's going to be real hard on this thin of a blade...it'll cool down too fast. Too late now anyway, but thanks for the advice. I'll try to remember next time, cause I know there'll be a next time.:grumpy:
 
Sometimes, having more meat on one side of the grind than the other will make a blade warp like that. Are you certain your grinds are even?

1/16" is pretty darn thin. That will make it prone to warp too. A lot of folks grind thin stuff after HT.

A good heat treater can correct bends if they're not too bad, but there is a limit.
 
I have the same issue with 1/16" stock. With ATS34 though, you can use plate quenching.
 
Plate quenching will help eliminate a lot of twist and warp.
I would not consider .1" warp in 11" length as "Pretty Crooked". Some warp is normal, especially in very thin stock. As was pointed out, any unevenness in the grind can cause a small warp in thin stock. I would suggest grinding the bevel post-HT on 1/16" blades. Use fresh belts, bare hands, and lots of dunking in water.

As to the straightening, just put in the oven at 400-450 for about 30 minutes and straighten the warp with gloved hands upon removal. If needed, repeat. Once the warp is gone, clamp the blade between two pieces of 1/4" stock and put the whole thing in the oven for 1 hour. That should take care of any minor twist/warp.
Stacy
 
I've read here (from some VERY respected makers) that rewarming a blade to straighten it, is not the same as straightening on the way down when hardening.

This thread seems to indicate it works just fine. :confused: Not fair! I'm too easily confused. :D

Rob!
 
i've used a lot of air hardening steels at 1/16" thick and you actually have a lot of time to straighten something out of the hot arse oven ! Plate quenching even too ! Sometimes plate quenching can cause warping though on something that thin (been there done that) especially if the crimps on the foil packet exceed thickness compared to the blade itself. Ask me how i know? lol.

have you seen how CROOKED some of these commercial cooking knives are in reality? Good god ! I'm amazed they got the scales on !
 
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