Warped blade

B

bigpapacolt

Joined
Sep 5, 2013
Messages
20
Hey guys,

So in my first attempt to heat treat a knife out of 5/32 0-1 steel I made several mistakes. First, I noticed I overheated the blade and let it heat too much on one side and not the other. This in turn, left me with a warped blade. The spine has a bow as well as the handle. Looks a little like an S. What do you recommend or is this even something that can be fixed? I've read where you can get three pins and put in the vise and also where people have clamped it to a piece of flat stock and put it in the oven to temper. Any help will be greatly appreciated!! As much as I HATE having made these mistakes, you can guarantee I won't be making them again! Lesson learned! :)
 
With every batch of oil hardening steel I do I have at least one that needs straightening. I run the first temper cycle and then clamp to a flat piece of stainless I have with some shims to give a slight over-bend. Run the next temper and check if it moved enough, too much, or not at all. Reclamp and do it again. Normally after the second temper I will only heat for an hour instead of 2.
 
Thanks Chris. So you would go ahead and run the first temper cycle unclamped, then on the second cycle shim it and retemper in cycles until straight? I don't have any stainless stock but could I use an old metal file to clamp it to as long as it's straight?
 
I run the first temper just to try to avoid any cracking or breaking due to stress. Make sure the file is straight. I had a heavy file I used once and the blade would not straighten, it was because the file had an S curve to it as well. Good luck.
 
I had an 01 chopper that came out with a slight bow over the entire length of the blade and tang (long distal taper to the blade and tapered tang). As Chris says, run the first cycle to relieve stresses. Then clamp. But don't be discouraged if it doesn't work the first time. Sometimes you need to raise the temperature slightly during subsequent temper cycles to get the steel to relax enough to move. It took me 5 two hour temper cycles to get mine straight.
 
You might want to consider this for next time. Get the blade at around 1200F and let it sit there for a few minutes then ramp up to 1475F . I think you may want to try keeping the blade in a fixture of some sort not lying flat but edge up. Even with that said I still warp O1 . Are you using a forge or a kiln ? And what are you temp do you use now ?
 
I used a coal forge. Just a DIY washtub forge. It was my first time using it. Worked really well but a rookie mistake and I left it in too long and didn't flip sides. Not sure of the temperature but made sure the metal wasn't magnetic. How would you tell the temperature of the metal. Infrared thermometer? Sorry for all the questions, I'm just wanting to learn as much as possible.
 
Thank you all for all your help! I'm going to try what Chris and Marc suggested with the tempering tomorrow. I'll report back with the results!
 
Something I learned that may help prevent warping in the future is to , use a bench vice with aluminum plates bolted to the inside of the jaws with a lip at the bottom of one plate (so the knife dose not fall threw). After oil quenching place the knife between the plate and tighten the vice, this keep everything strait and true while the knife finish cooling.
 
I do the exact same thing and it does work..If that fails I will just clamp it in the aluminum and temper with the plates on.


dogwood dan said:
Something I learned that may help prevent warping in the future is to , use a bench vice with aluminum plates bolted to the inside of the jaws with a lip at the bottom of one plate (so the knife dose not fall threw). After oil quenching place the knife between the plate and tighten the vice, this keep everything strait and true while the knife finish cooling.
Click to expand...
 
Just wanted to give you all an update. My once s-curved blade is now straight! After numerous tempering sessions while shimmed and clamped got it straight. I couldn't have done it without all of your help. Thank you! Now some time with the sandpaper, epoxy and a sharpening stone and this guy will be done. Thanks again!
 
Straitening during temper cycles is a great technique to master.

Now, put aside the O-1 and try steels that fit your equipments limitations. O-1 is awesome steel but requires spacific HT to be worth the cost.

Any 10xx series steels will give you as good results as poorly HTed O-1. [at half the price]

Now that you have your feet wet, read, try, ask questions, and continue on!! Welcome to the addiction!
 
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