First time for everything

[Shovelbuck]

Well, this is a first.
My plan for this day off was to build a couple knives, one for me and one to help finance a new gun. Now it looks like only one will get completed today.
I had just quenched this blade to harden. It was sitting on the bench when it happened. I picked up my small homemade anvil, an old cast steel iron and dropped it. Imagine the horror as I watched it fall in slow motion onto the hardened blade. Broke like glass. So...........had to make another. It is now safely sitting on the bench after being hardened AND Tempered!

 

[JakeWym]

That sucks. Funny how that stuff happens once in awhile

 

[JNRBRONC]

Jay,

A question on hardening/tempering.

It seems to me that a knife where the blade has the same hardness from edge to back might snap if someone was prying with it, say, trying to separate a knee joint while butchering. Is it common to try to have varying hardness from the edge to the back of the knife? I know this would be tougher to accomplish since you'd have to get the edge one temp while having the back another temp, but just wondering.

 

[Shovelbuck]

Good point. Factory knives are tempered in ovens where the temp is a constant throughout the blade. A lot of custom makers also use this method because the newer "high tech" steels require that type of tempering. It does make for a blade that is the same temper throughout.
Myself and some other bladesmiths still temper the way you are stating it should be done, with the spine being softer than the cutting edge. This is accomplished by using good, basic, high carbon steels and applying the tempering heat from the spine. Watching the colors change as the heat travels towards the cutting edge. When it reaches the proper color, stop the process. You then end up with a blade that that has some flex in the body but a hard edge.
Oven tempering is for sure the more cost effective way for production, but I prefer a more hands on approach to assure a good temper.