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6/6/2007

Tool Test -- Sharpening Machines: Are they better than a grinder and stones?


Tool Test -- Sharpening Machines: Are they better than a grinder and stones?
By By Tom Caspar; Art Direction: Patrick Hunter; Photography: Staff, Unless otherwise indicated
10/1/2001

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 high-speed 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 fit the 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 1). You must remove all of the factory-made milling marks about 1 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 offers 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.

Planer and Jointer Knife Grinding
In addition to sharpening hand tools, you can renew the edges of planer and jointer knives on some sharpening machines. They should offer both coarse and medium grinding because you’ll have to remove a lot of steel to get past deep nicks. Good machines have easily calibrated adjustments, well-machined jigs and clear instructions.

The Acid Test: Can each machine perform all the basics?
1. Lapping
The back of every new tool must be accurately flattened and highly polished.

2. Coarse Grinding
Removing nicks or dings to shape a new bevel requires hogging off a lot of steel.

3. Medium Grinding
The entire bevel is ground dead straight across to prepare the edge for honing.

4. Honing
The tip is highly polished at a precise, steeper angle.

Wouldn’t you like one machine that could do it all?

Vertical-Wheel Machines
Three vertical machines are very similar in design. A fourth, the Tormek, is much more sophisticated. Here’s how the three basic machines performed as a class. For details on individual machines, see the chart on pages 80 and 81.

Lapping - Barely acceptable. Using the side of the large wheel, it’s a slow operation yielding imperfect results. Maintaining the side of the wheel as a flat surface is difficult.

Coarse grinding - Okay. Use the dry wheel, but upgrade the tool rest (see Sources, page 80). The standard tool rest is too small and difficult to adjust. Toss it.

Medium grinding - Pretty good. You can’t overheat an edge on the wet wheel, but you might have trouble making the edge straight without a jig (see Recommended Accessory, at right).

Honing - Forget it. The wet wheels are too coarse to produce a polished edge, so you’ll still be honing with stones or sandpaper.

The Tormek
A favorite with hand tool users for years, the Tormek is a complete sharpening system at a fairly steep price ($390). You can go all the way from a rough to a finely honed edge, although coarse grinding and lapping on the wet wheel are fairly slow. Unlike the other vertical machines, you can change the grit of the wet wheel back and forth from medium to fine with an accessory stone grader ($22). Yes, it does work.

Renewing a bevel through medium grinding is quite easy using the Tormek’s sliding jig. You use the same jig to hone on a second wheel, which is basically a leather strop. All strops round over edges a bit, but if you’ve got the angles worked out and you don’t overdo it, you’ll get a razor-sharp tool.

The Bottom Line
Vertical-wheel sharpening machines are by no means complete systems. The basic vertical machines are best at preparing an edge for honing. Stick to the wet wheel, and you’ll never burn an edge. They’re a reasonable substitute for a high-speed grinder and a coarse stone, but aside from the Tormek, not a substitute for fine stones.

Vertical sharpening machines have both a slow-speed, coarse-grit wet wheel and a high-speed grinder.

Recommended Accessory
You’ll make straighter edges on any vertical machine by adding an Accusharp tool rest and grinding jig ($33 to $40, see Sources, page 80).

The Tormek features two slow-speed wheels: a wet one for grinding and a leather one for honing. There’s a well-designed jig available for just about every woodworking tool ($13 to $60 each).

Horizontal-Wheel Machines
Most of these machines are very simple: water drips from a reservoir on a rotating 1,000-grit waterstone. Reliant and Delta offer an additional high-speed grinder. The Veritas, however, is a dry, sandpaper-based system. Here’s how the wet machines performed as a class. For details on individual machines, see the chart on pages 80 and 81.

Lapping - Acceptable. Use the surface of the large wheel, either while it’s spinning or stationary. You’ll get a higher polish than a vertical-wheel machine produces, but it’s still not shiny enough.

Coarse grinding - Okay, but only possible on the two machines with a high-speed grinder. Upgrade their tool rests (see Sources, page 80) and you’ll be much better off.

Medium grinding - Good. The wet wheels work fine, but the standard tool rests on the single-wheel machines are too narrow and not equipped with jigs. It takes practice to make a consistent bevel. Delta’s jig works well. Some machines offer auxiliary tool rests for planer knives that are wider and accept a neat aftermarket jig (see Recommended Accessory, at right).

Honing - Acceptable, using the same wet wheel. Your tools will be sharp enough for general-purpose work, but you’ll have to finish with stones or sandpaper for truly keen edges.

Veritas Power Sharpening System
The Veritas is quick and clean, but this convenience comes at a pretty stiff price ($395). Clamp your tool in a jig, set the tool rest into one of seven pre-marked indents to establish the bevel angle and you’re all set. Changing grits by swapping discs only takes a few seconds. The honing disc is thinner than the coarser ones, so when you switch to the finest disc, you automatically raise the bevel angle by one degree. Now you can form a perfect, shiny bevel on the tip of your tool. This is a dry system, so you won’t make a wet mess. Hook up a vacuum to keep your shop free of grinding dust.

The Bottom Line
Horizontal wheels are finer than vertical wheels, so you get a sharper edge. A horizontal machine is a good substitute for a high-speed grinder and medium stones. The Makita (with accessories) and Veritas can replace your fine stones, as well.

Horizontal machines have slow-speed, medium-grit wet wheels. The Delta and Reliant come with additional high-speed grinders.

Recommended Accessory
Make super-sharp edges on the Makita, Delta and Reliant with a 2 In 1 guide ($15, see Sources, page 80). Grind your edge on the machine’s fine wheel, then add a roller to the 2 In 1 guide and continue honing on your favorite fine and superfine stones.

The Veritas Power Sharpening System is a completely dry machine. You can easily interchange a full range of self-stick sandpaper discs, good for up to 200 sharpenings apiece ($3 to $5 each).

Recommendations
If you don’t mind getting a bit wet, most sharpening machines are good replacements for high-speed grinders. But only a few machines can replace all your stones, and they cost almost $400.

What Will Work for You?
• If you’ve got a high-speed grinder and hate overheating your edges. You’re in the market for any wet machine. It’s impossible to burn an edge with one.
• If you don’t have a grinder. Look for a sharpening machine that has one, but count on upgrading the tool rest.
• If you don’t sharpen often or need a super edge. Look at the least expensive horizontal-wheel machines.
• If you prefer honing on a stone without a jig. Pick a vertical-wheel machine. It creates a hollow-ground bevel which is easy to balance on a stone.
• If you use Japanese tools. Go with a horizontal-wheel machine. Japanese laminated blades should be ground with a flat bevel only.
• If you use carving tools. Go for the wet Tormek and its jigs. It’s possible to burn a very thin edge on the dry Veritas.
• If you want to sharpen nicked planer and jointer knives. You better have some patience. Setting up the jig and removing a lot of steel takes time.

Do You Need One At All?
Not really. Here’s a complete, low-cost alternative sharpening system:

Lapping - A piece of 1/4-in. plate glass, sandpaper and a low-tack spray adhesive. Cost: about $10.

Coarse and Medium Grinding - A slow-speed grinder with white wheels, an aftermarket tool rest and a diamond dresser. Cost: about $155.

Honing - A combination 1,000/6,000 waterstone and a honing jig. Cost: about $40.

Sources
Accusharp tool rests, grinding jigs and wheel-dressing kits to fit Delta, Reliant and Grizzly grinders are available through Penn State Industries, (800) 377-7297, www.pennstateind.com

2 In 1 honing jig, #02.26.01; $15 is available through Highland Hardware, (800) 241-6748, www.highlandhardware.com

Veritas Tool Rest, #05M23.01; $33 and the Veritas Grinding Jig, #05M06.01; $16 are available through Lee Valley Tools, (800) 871-8158, www.leevalley.com

Delta 23-710; $160.
Equipped with a good jig for chisels and plane blades, this machine is great for coarse and medium grinding, but you must further hone by hand for a really sharp edge.

Makita 98202; $260.
A good machine with great accessories. Comes with a jig for planer and jointer knives. If you’ve already got a grinder, buy this and you’ll have
a complete sharpening system.

Veritas Power Sharpening System; $395.
Wow! It does it all. Combining dry sandpaper technology and innovative design, this user-friendly machine easily tops the field.

Reprinted with permission from American Woodworker magazine, ©2001 Home Service Publications, Inc., an affiliate of The Reader’s Digest Association, Inc., Suite 700, 2915 Commers Drive, Eagan, MN 55121. All rights reserved.