Monday, August 22, 2005

Putting an edge on it

Over the years I've used all kinds of things to sharpen knives and axes. Stones, sticks, sanding belts and so forth. They've all got their good and bad points. A good stone will put a fine edge on, but can take forever, and you really need at least two stones: a medium for setting up a good edge bevel on a new blade or repairing a badly dulled or damaged edge, and a fine for finishing the edge off. Mind you, this method has worked for several thousand years and still does the job quite well. One of the best types of stone I've found is the Norton Crystolon for fast cutting, and an India or Arkansas stone for finishing the edge. Side note, a hard Arkansas does a pretty nice job of putting a polish on trigger or other action parts, too.

There are some very nice ceramic sharpeners out there. Some are sticks, round or otherwise, some are flat rectangles. I've got some small ceramic stones, about 2x3" I found at a surplus store that are great for touching up an edge, pretty fast-cutting and clean up with water. There are round ones with handles called 'crock sticks' you use like a butchers steel. I've also used a Spyderco sharpener. It's a plastic base that holds two triangular ceramic sticks, corners are medium grit and flats are fine; you put the sticks in the base and draw the edge of the knife along the sticks, one side and then the other. Not a bad tool, if you're careful you can vary the angle of the edge to get different bevels.

Then there are some systems that use a fixture that holds the blade, and small stones you attach to guide rods. There are holes in the fixture the rods go through to set the angle, and you draw the stone along the edge- Lansky is a common one. These work very well, and if you have trouble keeping the edge at the same angle as you work, this is a good system.

I mentioned sanding belts. I use a fine belt, about 240 grit, to do the initial sharpening on blades I make, then either a fine stone or steel to finish it. It's fast, but if you're not damn careful you can overheat the edge in a spot, or take off too much. And if I want a really, really fine edge I take a hard felt buffing wheel, which will keep a nice flat surface, load it with a fine polishing compound and finish the edge with that. Not that good for heavy-cutting edges, but if you need a really smooth, fine edge it's wonderful. It also has the added advantage of being a bit dangerous; you get careless with that buffed edge doing the final touch, and you'll be bleeding before you realize you've been cut.

Yes, knife people are a bit strange.

One of the tools I use most, because it a: works and b: I can carry it around, is this Gerber steel:

The narrow edges is medium, the flats are fine. It folds into the leather for carry, and the leather gives you a handle when you use it. I've used this thing on knives, axes, swords and scissors with good results. It doesn't show in the picture, but the leather's a bit beat up from the years and use, but it's still going strong. When you're finished, wipe it lengthwise with a cloth and a bit of oil and the metal bits come out of the grooves and it's ready for next time.

I haven't much experience with the various diamond stones. The idea is good, I'd guess how one works depends on how well the diamond dust is bonded to the substrate. I have known people who swear by them.

In history they've used- still use- everything from a smooth rock from a riverbed to a building block to sharpen tools; there are stones in Hadrian's Wall hollowed out in the center from countless soldiers touching up a blade on them. But it is a bit easier with something intended for the purpose.

No comments: