While I am not the most experienced leatherworker around and have never actually used a head knife. It is also on my list of tolls to make. I have however been maiking knives and other tools for quite some time. Old saw blades with out the added carbide teeth should be excelent blade steel As would be the 0.90% - 1.03% steel mentioned by the last poster. The issue with any home made cutting tool is that you must either make it from already hardened and tempered steel or you must be able to do the herdening and tempering yourself. Cutting and shaping hardened steel isn't very easy and if you get it to hot while grinding you will remove some of the temper resulting in a softer area.
I think making a head knife sounds like a great project. But it is the perfect example of investing $200 in labor for a $50 item.
