Machines

Are they better than a grinder and stones?

By Tom Caspar

I know a guy who uses a belt sander to sharpen his hand tools! Don't laugh, it works—sort of. There are dozens of setups you can use to sharpen tools. Many woodworkers have grown accustomed to using a highspeed grinder and stones, but a grinder can burn your tools and stones are a hassle. Wouldn't you like a single, foolproof machine that could do it all?

The Test

We took a hard look at horizontal and vertical sharpening machines to see if they lit die bill. With the aid of a panel of intermediate-skill, non-professional woodworkers, we rated the machines on how well they performed four basic tasks:

1. Lapping

You only have to do it once, but it's gotta be done right. Lapping makes the back of a tool dead flat and highly polished (Photo l). You must remove all of the factory-made milling marks about l in. back from the tip. This tedious and exacting process is a bear when done by hand. If you can get a machine to help, by all means, go for it.

2. Coarse grinding

You won't need to do it very often, but coarse grinding is essential for restoring old and abused tools. It removes a lot of metal to form an approximate bevel (Photo 2).

You don't need to precisely calibrate the grinding angle, but an easily adjustable, wide tool rest otYers the most control.

3. Medium grinding

You'll renew the bevel made in this operation quite often (Photo 3). At this point, grinding becomes fussier. The bevel you produce should be absolutely straight across and accurately angled to within a few degrees. This makes honing much easier. Machines with good tool rests and jigs are easiest to use, although you can get decent results without a jig if you have a steady hand.

4. Honing

The faster this goes the better, because you'll be honing over and over again. You refine the tip of the tool until it's razor sharp at a single precise angle (Photo 4).Three things are critical: controlling the angle of the bevel, defining the shape of the edge (dead straight or, in the case of some plane blades, very slightly curved) and producing a mirror-smooth polish. Machines that can do all three things well have a good tool rest, a good jig and fine abrasives.

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