Need some help warped blade

D

Dr Feelgood

Joined
Jan 3, 2011
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I have completed one knife from start to finish now and was on my second blade. Its a rather thin blade of Aldos 1084. It got a little hot in places during initial grinding. I wasnt sure where to start in the heat treating process. So I just went right to anneal. I used this here im sure most of you recognize Cashens info. http://www.knivesby.com/knifemaking-Kevin-Cashen-treating-1084.html
So im the heat treating oven at 1500 soaked for 10 minutes, cool with the oven slowly.
The blade came out in a slight "S" curve. I then heated with a torch and spent the last two hours banging it somewhat flat on the anvil. Did I completely pooch this one ? What do i do with it from here ?
I think it warped because it was too thin (guessing) its flat enough now I could correct it with a little grinding so long as it doesnt warp anymore.
Im thinking of... Normalize three times then anneal... Harden at 1500 and quench. Following Cashens instructions to the letter this time. Then draw the hardness back by soaking at 400 degrees for ten minutes x three. Being such a thin blade I have a feeling it will warp even worse along the way. Im just not sure where lol.
 
Quit annealing a blade ready to be heat treated. Annealing softens the blade so that it can be machined. If you have it ready to go then don't waste your time annealing. Instead this is what I would personally do with a such a badly warped blade: Heat it to around 1200 and clamp it to a piece of angle iron (use at least 3 clamps) or between two thick pieces of steel and let it cool. This should remove the warp. Then I would normalize it (1600, 1500, 1400) while letting it cool to black after heat. Then I would heat treat it as you said but before you temper it put it back in the angle iron to keep it straight. You could also use pennies or small washers to shim the blade as needed.

Good luck.
 
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Lets see... Heres a picture as well. The warp is hardly noticeable by the eye now.
 
jawilder said:
Quit annealing a blade ready to be heat treated. Annealing softens the blade so that it can be machined. If you have it ready to go then don't waste your time annealing. Instead this is what I would personally do with a such a badly warped blade: Heat it to around 1200 and clamp it to a piece of angle iron (use at least 3 clamps) or between two thick pieces of steel and let it cool. This should remove the warp. Then I would normalize it (1600, 1500, 1400) while letting it cool to black after heat. Then I would heat treat it as you said but before you temper it put it back in the angle iron to keep it straight. You could also use pennies or small washers to shim the blade as needed.

Good luck.
Click to expand...

Thanks thats perfect! Just one question. I take it the normalize is detached from the angle iron ?
 
Dr Feelgood said:
Thanks thats perfect! Just one question. I take it the normalize is detached from the angle iron ?
Click to expand...

That is correct. The angel iron keeps the blade straight as it cools. I like to clamp the butt of my handle in a vise or hold it while the blade cools during normalizing because it will warp if you lay it down.

Most blades with extreme or uneven grinds will warp during heat treat. Using the angle iron during the temper will help straighten them. If you do notice a warp out of the oil, clamp to the AI and temper at only 350 for an hour then check the straightness of the blade. Tweak as needed with the pennies and raise another 15 degrees or so then check after another hour. Once it is straight then temper at your desired temp.

One word of caution: Don't clamp down too tight or you might snap the blade. Ask me how I know ;)
 
Gentlemen, what are you clamping with when you straighten during temper? C clamp?
Would sandwiching the blade under a weighty piece of steel work instead of a clamp?
 
I use cheap harbor freight c-clamps. I wouldn't use heavy pieces of steal because you wouldn't be able to adjust the blade as well. With the c-clamps and washers/pennies you can tighten the blade in such a way that it over corrects the warp. Put the washer where the bow is and tighten it so that it bows the other way a bit. You couldn't do that with just a heavy piece of steel on top. Also, it would take longer to temper because of the mass of the plates.
 
Interesting... I was thinking the same thing about the plates. Is it correct to say then that a mild bend that is barely noticeable can be corrected with the final shaping/grinding/hand sanding ? Or will this make it the problem worse ?
 
Dr Feelgood said:
Interesting... I was thinking the same thing about the plates. Is it correct to say then that a mild bend that is barely noticeable can be corrected with the final shaping/grinding/hand sanding ? Or will this make it the problem worse ?
Click to expand...

That's usually the case, yes.
 
I was thinking that the plates would be pre-heated, but I see what you mean about the over correction. I guess clamping the hardened steel just makes me nervous.
But then the weight is probably no gentler...
 
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