Double Edge Blade Hardening/edge quench

[SamLS]

With a double edge blade like a "smatchet" whats the best method for hardening and quenching the edges of the blade and keeping the tip hard. If you heat and quench one edge at a time I would think you would anneal the opposite edge just back fron the tip. Would this be an instance where I would want to use the clay method and put fire clay at the center section and quench the blade in this manner. Thanks

[mete]

You can't quench one side then the other.You'd never get uniform results side to side . But you can use clay, just coat the center of the blade.

[AwP]

You could also do a differential temper rather then a differential quench, i.e. draw the center to a softer temper with a torch being careful not to effects the edges. You won't get a pretty line, but funtionally the effects are pretty similer.

[GHEzell]

I'm with Mete on this, fireclay is the only way I've ever pulled it off. Wrap the clayed blade with non-galvanized iron wire to help hold the clay in place while heating and quenching.

Also, be sure your steel is sufficently shallow hardening, this wouldn't work too well with O1 or L6!

[SamLS]

Thanks, I got a piece of O-1 as surplus from another job and intend to use it. I always wanted to do a smatchet. I suspect its due to their size they never caught on with the troops of course the Kurkuri is probably larger. I would like the blade differentailly hardened. If I heat it in a forge with a clay coat on the blade and handle area will the edges heat up enough first to just harden the edges with O-1. I found some info on this technique for 1085 and a sword web page but I know its hardening caracteristics are much different than O-1. I only have one piece and want my first try at this to turn out favorably thanks for the advise.

[Ed Caffrey]

I'm with Mete on this one. Clay is going to be about the only practical way to do it. In some instances I have had difficulty with clay hardening O-1, simply because is does a bit of air hardening qualities.