Can A Bowed A2 Blade Be Straightened?

[redsquid2]

I sent a batch of A2 blades to Texas Knifemakers Supply for heat treat. Three out of the four came back bowed. If you looked at them down the spine from butt to tip, they were are all three bowed to the left.

I put one in the vise, and I braced my feet and I leaned into it. It snapped. It was .093, and it had a weakness, in that it was a thin, narrow blade with a relatively big pin hole. It broke right where the pin hole was.

The others are .125. They don't have that weakness. I.e., they are relatively wide, and thick, with smaller pin holes. Maybe I can bend them straight?

Is there some way you can tell when you are pushing it to the limit, and it's about to snap?

Thanks,

Andy

 

[AVigil]

Wow...you are a brave man bending a cold blade.

How about giving a try using the method Rich Marchand describe here?

 

[Don Nguyen]

Here's what AVigil is talking about: http://www.bladeforums.com/forums/showthread.php/838681-Straighten-During-The-Temper

I use that method all the time.

 

[redsquid2]

Thanks for the info, guys. I don't have a heat treat oven. Would there be any problem using my kitchen oven? I think my kitchen oven is hot enough, because the AKS Web site says, "Temper: At least twice at 400°-1000°F for 2 hours minimum each time. 0Cool to room temperature between tempers." My kitchen oven can do 400 degrees.

If I can't do it myself, could I just send the blades to another heat treater and they would make them straight, as part of the HT process?

 

[Jason Fry]

Try it in the kitchen oven. 400, then if that doesn't work, try 450. Won't hurt the steel, and won't hurt to try.

 

[redsquid2]

Try it in the kitchen oven. 400, then if that doesn't work, try 450. Won't hurt the steel, and won't hurt to try.

OK. Thank you, Jason.

 

[LRB]

You can do it more simply using a torch by heating the apex area of the warp in the spine with the blade in a vise, then over flex and pour water on the blade. Just don't allow the heat color to go to the edge.
They should not have been returned to you warped!

 

[redsquid2]

They should not have been returned to you warped!

Well, I guess I got what I paid for. TKS has all that disclaimer language about their heat treat, so I'll just say Lesson learned and move on.

 

[redsquid2]

You can do it more simply using a torch by heating the apex area of the warp in the spine with the blade in a vise, then over flex and pour water on the blade. Just don't allow the heat color to go to the edge.
They should not have been returned to you warped!

I tried a torch-type cigarette lighter. I didn't notice any change in the color of the steel at all, but I swear I was able to bend it a little.

 

[AVigil]

Seriously do something like this http://www.bladeforums.com/forums/showthread.php/838681-Straighten-During-The-Temper

I have used in on many blades without fail and so have many other makers.

No need to dick around when an easy fix is right in your kitchen

 

[redsquid2]

I failed to mention I did look at the Rick Marchad thread, and I tried the oven method twice in the past two evenings. First cycle was 400 degrees and just over two hours(Wednesday night). Second cycle was 450 degrees and just over two hours (last night). Not much effect. I am going to try it again tonight while over-bending more.

Added note: I guess since it was already tempered, I don't need to leave it in there so long; just long enough to heat the steel all the way through.

I will return and report.

 

[AVigil]

try shimming it more if it does not work. Also I take it right out of the oven still in the jig and run it under the faucet to cool it down fast. Then take it out of the jig and see how it worked.