||[Sep. 3rd, 2003|10:18 pm]
Over the long weekend, I broke out the makita doughnut wet grinder and went to work on the tantos.
Now, this is something that would make a traditionalist cringe. You're supposed to do this by hand on stones clamped under your foot by a crooked piece of wood, carefully keeping your eyes over the work so that you can see exactly what's happening on the edge, wearing the steel away gently to reveal smooth, flowing curves with nary a straight line in sight. If you move at more than about half an hour per inch, you're going too fast.
Fuck that. I've got five knives to finish up. A drizzle of water, turn on the stone at 700 rpm, and eyeball it.
I used the three available grits -- a very coarse grit (about 120 grit or so -- like a coarse india stone), medium (1000 grit) and fine (6000 grit). The coarse grit is one I've only ever seen offered in one catalog, from a company specializing in japanese tools. It does a fine job of roughing off metal, while slow enough and cooled enough by the water drip that it worn't burn the steel. Since I generally leave a couple hundreths of an inch of edge thickness, this works out pretty well for the initial "base" grind. I leave a bit of a glint of light along the edge, as getting too close to a final edge can result in problems with the profile -- at 120 grit, you can accidentally remove a considerable amount of metal in a hurry.
Once all five were base ground, I stepped up to the 1000 grit. Now, you might think that from 120 to 1000 grit is quite a leap, but the stone in question is a fairly agressive stone, at least to start with. Keep a steady drizzle on it, and it will remove the grind scratches from the 120 and take the edge down to a smooth, sharp edge. As it grinds, grit breaks free of the stone, and forms a slurry that acts as a polish, resulting in a fairly smooth finish -- not quite mirror, but enough to see details of the lights overhead. At this point, it'll shave your arm cleanly, but we're not done.
The last stone, 6000 grit (the "king" stone), will leave a mirror polish. Unlike the other stones, you don't have to soak it, just drizzle some water on it and occasionally splash some more as it seems to need it. This stone will remove the traces of the medium grit, and give you quite the special edge. Wave the blade above your arm in the right way and hair just falls away from the edge, cloven in twain without any scraping or pulling. I like it.
Next steps: the edge is polished, but the body of the knives are still rough. I'll be taking them to the belt grinder and polishing them up, taking the polish to the edge, and smoothing out some of the grind lines that have crept into the work by the sharpening step. I have sharpened now, not after the whole knife is polished, as with Japanese knives and swords the sharpening is part of the polishing. If I was traditionally polishing, I would have continued the sharpening/polising process from the edge to the spine of the blade before moving on to the next stone. If I had the time, I'd certainly do it that way, I've done it before, and the results are great. Sadly, time is short, and I'd like to finish these off soon.
Once the polish is down to, say, about 6000 grit (gotta love modern abrasives), I'll use my special secret technique for bringing out the hamon, then do a little light etching to darken the steel a bit. More on that later.