David Weaver
...to durability test a unicorned japanese chisel edge.

I have some chisels that I need to set up and sell, but two were over hard. I figured they'd be good chisels, but they would chip just sharpening.

This is sort of in line with the accommodation thing, too. I find once in a while that something was just defective, but most of these chisels are probably made of yasuki steel (now owned by hitachi) or hitachi if a little newer and it's not likely the makers had a process that would've done much wrong to them, but not unlikely that the makers would've expected a skilled worker to temper them back a little more themselves.

These days, I get the sense that the reason some makers make chisels a little soft is because internet jockeys and enthusiasts are buying them and they don't so much as want to even have a stray hammer strike. Taking them apart and tempering them back a little bit is out of the question.

I tempered two of these, though - I guess in fairness, one was just over hard but would hold an edge paring - it's horrid to sharpen, though. Fresh alumina paper and it skates. The other chipped in sharpening and then chipped worse paring an easy corner off of cherry.

Both tempered back to 325º F and both would still be better chisels if they were tempered a little bit more to aid sharpening, but I gave them the unicorn.

I chopped 4 inches plus a little of a maple stick 1 1/2 inches tall and then my shoulder had enough (750g gennou - don't spare the rod). This chisel has not been fully set up yet, so there are still deep marks from initial flattening making it to the edge.

There is so much support at the very tip that even after this abuse, the edge is not giving up at deep lateral sharpening marks. This is really a surprise to me. I've always oriented the last scratches to avoid damage at these marks. subjectively, sharpness is better ,too, but I don't know that I could prove it.

I tried measuring temperature of the chisel, but my non contact thermometer only said +10 degrees F, and that didn't seem right by feel. After subjecting the 1/2" chisel to the same torture, same giant gennou, but half of the distance chopped or a little less, I could push a crayon onto it and have the crayon melt.

(sorry about the picture darkness -software decided that was good).