It was going good until...

[Thadbow]

After looking at all the brutes here lately and reviewing Joe Keesler's book, I decided that I was going to fire up the forge and make the attempt.
   I have tried to use a heavy hammer and go at a pretty good speed in the past but I quickly realized that well, I needed to slow down and take smaller bites.
   In his book it states that you want to know what you are going to do with that piece of steel before you pull it out of the forge and I really tried that with this knife.
 

 

 When I hardened the blade, I pulled it out of the oil to check for any warping and noticed that there was a distinct warp along the edge about the size of half a dime.  I have straightened long warps at this point but never something this small.  Long story short... I broke the warp completely off.
  After looking at the break, I could see that this certain section of the blade was thinner along the edge than the rest of the blade... Thus the warp

 

I snapped some pics and put it down on the bench and came up with two questions:
What would of been the proper way to go about a warp along the edge like I had?
What would be a good process for salvaging the lower half of this blade?
Hopefully somebody can learn from my mistakes...
Thanks,
Thad

[Lin Rhea]

Thad,
       Am I to understand that you came out of the quench oil and hammered on the blade? If so, you can expect it to break. After about 40 seconds from descending below 400 degrees, the blade gets hard and is at it's most brittle state. You HAVE to draw it back before attempting any straightening.

Better yet, prevent it from happening by grinding the edge to an even thickness. It needs to be at least .020 thick, maybe .025 thick for this size knife. Any thin spots will provide it with an opportunity to warp or wrinkle along the edge. It amounts to a weak spot. The strain along the entire length of the blade then is relieved all in the weak spot. If there is no weak (thin) spot, the strain is distributed through the entire length with a lot less likelihood of warpage. Then the strain is reduced in the draw.

If you think there is a thin spot, you should grind up into the blade and even things out before the quench.

[Thadbow]

Lin.
  I actually came out of the quench after about 6sec and checked for any warping.  When I noticed the distinct warped area I put the blade on the bench and applied some pressure with a piece of osage while the blade was still hot.  As I was holding down on it it popped like I knapped it.

  Thank you for the detailed explanation here, I really appreciate it!  It never occurred to me how important it would be to have even thickness down the edge but now I see why!  
Live and learn...
Thad

[Lin Rhea]

Yes Thad. Its experiences like this that will stay with us. Believe me they make an impression. Your forging looks good by the way.

[Thadbow]

Thanks Lin, that means a bunch coming from you!

Tonight I drew back this piece and re-shaped it into a leather working tool and... forged out another blade.
  I also got the rough grinding done and hopefully I can HT this weekend....I WILL be sure to have an EVEN .025 across the edge this time before the quench....

Thanks,
Thad

[Ray Hammond]

Been there, done that, got the t-shirt!!!!!

I like that blade shape a lot....nice work on the finger area too!