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Differential Temper on Double Edge Fighter


Jan 25, 1999

It is common for a big camp knife to be heat-treated with hard edge and soft spine (assume it's made of a steel that can be done). My question is, in case of a big figher with false edge at the back, what would a knifemaker do regarding differential-tempering? Is the softer part still along the back of the blade, which means the false edge would not hold an edge as well as the primary age? Or can it be done in a way that gives hard edges for both while having a softer core along the middle?

Thanks in advance.

A differential temper is not done on a double edged blade (whether partial false edge or true double edge). A certain knifemaker who forges his blades out of 01 told me that this is because, first, you need the secondary edge hardened, and secondly, the secondary edge reduces the cross section of the blade so that it is flexible enough to not need a differential temper. Go to KFC and ask him directly if you want it right from the DOG's mouth. Walt
I suppose it might be possible with a good clay temper..... The false edge might be drawn back a bit more, to compensate for loss of toughness somewhat.

If you are referring to knives like the Panther and Wild Thing, they are differentially tempered. There is a visible hamon, and the false edge is softer than the primary edge. Since the false edge is not going to be used for anything but social work, I don't see a problem with this. I have touched up the false edge on my Panther and it is much easier to sharpen than the hardened edge on my other Mad Dogs. Of course these blades are ground not forged, so I may be talking about the wrong knives.
To differential temper a knife requires that the part you want to harden be heated to the critical point of that particular steel and cooled at a rate fast enough to harden that part without hardening the rest of the blade that doesn't require holding an edge. You can differential heat treat with clay or certain types of cement applied to the parts that you want to stay soft. I use the heat treat oven to do this as it brings the whole blade up to temp. and when you quench, the center of the clay will cool to slow to harden the steel. This usually will only work on fast quenching type steels; 1070,1095, 5160, 52100, etc. O1 will not form a temper line due to the approx. time needed to harden (10 sec.). It doesn't work as well on knives with less than a 6 inch blade either.
If you temper at least half of the blade, the back of the clip for about an inch will be hard any way. That will be what is most in contact on the backswing anyway. If I were to carry a knife with a sharpened clip(a few times), don't let ANYONE hold it because they always have to touch it and start bleeding. A dagger is about as legal here as a sharp clip and every one knows both sides of it are sharp. Didn't mean to ramble. Ray Kirk
01 does have a temper line (hamon) when properly treated. I have six Mad Dog blades that back this up. I am sure there are many more forumites that will validate my observations.
Does anyone know of these blades being made of 01 with an overall super elastic temper, rather than a differential temper?