Warped 26C3 Blade - A Little Fixing Tool

[MTBob]

With my first venture into thin 26C3 (.78") I found an ugly 1/32" lengthwise bend/warp after HT in Parks 50. After tempering at 350 the steel is around RC 64ish, per AKS graph. The warp would not move with cold bending. I read that placing the blade back in the oven and coming up to the target temp again, would allow the steel to move with pressure applied. As hard as this blade is, I was skeptical.
So, I cobbled together a simple little fixture that allows me to place force on the blade in various places. The center yoke and end fulcrums are all unattached to the base and can move to locate the pressure at the apex of the distortion - following the golden rule: If you can't make it perfect, make it adjustable.
After an hour soak at 350 the blade came out near perfect.

 

[SS369]

Good set up! How did you decide how much to over bend it?

 

[MTBob]

How did you decide how much to over bend it?

It was a guess. I deflected it back in the same amount of the initial warp, about 1/32" beyond straight.

 

[Dennis Morland]

That is a nice set up. Easily repeatable.

 

[opaul]

Good tip. I use a C-clamp with the base and scrap pieces of 1084 for the shims.

 

[Doug Lester]

I like the jig. I use a short length of angle iron with C-clamp to apply the counter bend and how many ever cent pieces I need on the ends to set the degree of bend that I need, but like I said, I really do like the jig.

Doug

 

[Drew Riley]

I like it. I need to make something similar one of these days.

 

[REK Knives]

that's amazing, great job Bob! I love seeing everything you come up with