Another way to take care of warped blades

Tom Lewis

Tom Lewis

Joined
Feb 24, 2000
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I quenched a 26c3 blade and it had a warp. There are several ways to deal with warps but the best way I had found so far was to temper the blade once for two hours, let cool then start tempering the blade again. After the blade gets up to the temper temperature I would take it out put it between a jig with two bars on one side and one bar on the other, put it in a vice and over correct the warp. That usually worked.
Well, on this last blade I tried several times to correct the warp and it wasn't happening. So I really cranked down on the vice and the blade warped the other way. So I put it back in the Paragon let it get back to the temper temperature, (400 degrees) took the blade out, placed it on the anvil and used a ball peen hammer to straighten. I was tired of fooling with this blade and if it broke I really didn't care. It worked like a charm.
I have only done this once. Has anyone else ever tried this?
 
I've never tried that, but i suppose it's similar logic to the classic shimmed temper. I might try it next time i get fed up with a blade :P
What's this carbide chisel method?
 
For the idiots among us(mostly myself) just to clarify the hammering is done on the concave side of the warp.?.?.?.?
 
Alex Topfer said:
I've never tried that, but i suppose it's similar logic to the classic shimmed temper. I might try it next time i get fed up with a blade :p
What's this carbide chisel method?
Click to expand...
Search carbide chisel here. I’ve mentioned it in detail a couple of times
 
When I straightened my blade I had the concave side on the anvil. It took about two seconds to straighten the blade. Now I don't expect this to work on steel like AEB-L or 154c,but it did work at least once with the 26c3 blade.
 
3fifty7 said:
For the idiots among us(mostly myself) just to clarify the hammering is done on the concave side of the warp.?.?.?.?
Click to expand...
Yes. Below is a rather lengthy video by Murray Carter about straightening blades. Skip to around 15:30 to see the carbide hammer.

 
Yes, but even a hardened hammer ball would wear down very fast hammering on a hardened blade. The actual contact area is very small. You aren't actually hammering the blade, but are peening tiny divots in the surface to stretch the one side and correct the warp. Done right these will grind away in finishing.
 
Stacy E. Apelt - Bladesmith said:
Yes, but even a hardened hammer ball would wear down very fast hammering on a hardened blade. The actual contact area is very small. You aren't actually hammering the blade, but are peening tiny divots in the surface to stretch the one side and correct the warp. Done right these will grind away in finishing.
Click to expand...
That is exactly what Tom Lewis Tom Lewis done with hammer ball , with less damage on steel .I mean more shallow divots which will be much easy to grind .Carbide tip make deeper and sharper divots ....Maybe dedicated ball hammer from steel which can harden much more would be better then carbide ? Or carbide tip sharpened in ball shape ?
 
What I have understood is the best method is inserting a round of carbide into the ball and grinding the whole ball end to a rounded and even surface. I would suspect that a 1/4" to 1/2" radius would be good.

I will admit that I don't use this method on blades because I rarely have a warp to correct.

I do use several radii of hardened ball peen hammers for decorative work and silversmithing to make curved surfaces in copper, gold, and silver. You can take a flat sheet of 12 gauge silver and raise it into a bowl, or even a pitcher, with the right hammers. I have a big block of mokume that I plan on working into a bowl by this method.
 
Regarding the radius, JTknives JTknives recently commented that the maximum radius should be 1/8" in the AEB-L warpage woes thread.

In the same thread @PEU commented that he prefers hammers that create an elongated divot. His preferred hammer does not have a carbide insert and you can see his straightening hammer collection In this post.

The hammer I made used a 1/4" carbide insert and you can get an idea of the tip shape from the picture below. I have used this hammer on a few AEB-L blades so far and it works great. I plan to grind the other half of the carbide piece into a flat head insert to test, but have been too lazy because the ovoid tip has worked so well.

XplUDvp.jpg
 
i used a carbide glass bit epoxied into a hole drilled into a ball-peen hammer. The bit was rounded. Its a bit ghetto but works great.

I posted this method on another forum a while back and was harshly shot down by someone with way more experience than myself for creating stresses in the blade. Has anyone done and testing on peeing and strength reduction?
 
Well, let me try to explain what I did. I know about the carbide tipped hammers and they obviously work.
With the warped blade of 26c3 I heated it up to the tempering temperature of 400 degrees. Took it out of the Paragon oven placed in on the anvil with the bowed side up and with a ball peen hammer hammered it straight. I didn't hit that hard and didn't leave any divets. It took just a few light taps and the blade was straight.
When I say bowed side up what I mean is if you look at a bow that shoots arrows. One side will have the string and the other side the bow. I put the string side on the anvil and hit the bow side.
I know when you use the carbide hammers you put the bow side on the anvil and hit the string side.
I have only done this once. It seemed that at the 400degree temperature I was able to straighten the blade without cracking it.
Next time it may not work for me. I just wondered if anyone else had tried this method.
 
I have straightened thousands of blades using surface peening, Works like a Charm. I actually converted an old sewing machine into a peening machine. When you have to straighten 25-50 blades a day you quickly realize you need a faster way lol.
 
I haven't yet had a warp I couldn't take out during temper. I get the blade up to tempering temp, pull it from the oven and clamp it to a large, surface ground piece of steel with some small spacers behind the blade in a way that aloows me to "over bend" the warp to the opposite side about the same degree. I leave the blade clamped during temper and it almost always comes off that clamp straight or close enough the second temper handles it.

If a quick hammering would achieve the same, it would have more control so I may look into this option.
 
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