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A Bargain Honing Jig, and How To Improve It

WHEN I FIRST LEARNED HOW TO SHARPEN, I bought a very simple and inexpensive honing jig made in England by Eclipse.Today, the same jig is widely available under many different brand names and often costs less than $15. It works quite well-I've used mine for years-but I've made a few small refinements to it.The jig's body is aluminum, so it's very easy to modify using a file or disc sander.

The jig has two positions for clamping tools: an upper ledge for plane irons and a lower pair of V-shaped grooves for chisels.To set the honing angle, you measure the distance from the tip of the blade to the body of the jig. Here's what you can do to make this good jig even better:

• Flatten its face. For accurate and repeatable projection measurements, the two front faces of the jig must be square and even with each other,The easiest way to flatten the faces is by placing the jig on a disc sander's work-table and gently pushing it into the disc {Photo 1).

Widen the chisel slots. Many chisels don't fit very well in the V-shaped grooves because their sides are too thick. Clamp the jig in a vise and use the edge of a 6" or 8" mill bastard file to widen the grooves to fit your tools (Photo 2).

* Make a projection jig. You don't need a ruler to measure a tool's projection-use a stepped wooden jig instead (Photo 3). It's more convenient, more accurate, and easily repeatable. I use a single 30mm (about 1-3/16") projection for most chisels and plane irons. This creates a 30" bevel on a chisel and a 35° bevel on a plane iron.

* Add a microbevel setting. I added a second side to the projection jig that Is 2mm (about 1/16") shorter than the first side, which increases the bevel angle by about 1To sharpen an edge,I use the normal 30mm projection on medium and fine stones (side #1), then reset the projection to 28mm (side #2) and hone on a superfine stone.

* Form a back-bevel ramp. Adding a back bevel to a plane iron makes the iron easier to sharpen (see Back Bevel Avoids Lapping, page 58).To make a back bevel using this jig, you just turn the jig over and rest its top on your stone (Photo 4). Unaltered, the jig produces a back bevel that's quite steep, so I used a disc sander to grind down the top of the jig, sloping from front to back.

Angles to Remember

TO KEEP THINGS SIMPLE, burn these three numbers In your memory banks: 25°, 30° and 35°.These are the three most commonly used angles when grinding and honing chisels and plane blades.

If you prefer to grind and hone your tools with a single bevel, just remember one number for each type of tool.

If you prefer a double bevel, make the grinding angle 5° less than the honing angle. A general purpose chis el, for example, is ground at 25° and honed at 30°.

The most widely used honing angle for a bench plane's blade is 30°. I prefer 35°, because a steeper edge lasts longer.

ocTOBEftf HOVE MBER 2009 www.fimeiicanWoodworker .com 61


The Hollow-Ground Bevel: What's the Big Deal?

THE NAME "hollow-ground bevel" has been widely misused. I'd like to set the record straight as to what a hollow-ground bevel is, what it's good for, and when to avoid it. It's simply a concave bevel-the natural result of using a grinding wheel. The wheel is convex, of course, so it always creates a bevel that's concave. A tool with a hollow-ground bevel Is easier to sharpen by hand, without the use of a jig.The biggest problem with honing by hand is holding the tool at the correct angle with every stroke. A hollow-ground bevel helps you find and maintain that angle, so there's no wasted effort.

With a hollow grind, you simply rock the tool up and down until it locks in place, resting on the bevel's heel and toe.Two points of support make the difference-it would be much harder to feel the correct angle if the bevel were flat, rather than concave. That's why we have arches in our feet-they make balancing easier.

I often sharpen chisels by hand, without a jig, simply because it's so easy. Ditto for plow plane and rabbeting plane irons that are awkward or impossible to hold in a jig. I do use a jig for honing standard-thickness bench plane Irons, though. Even with a hollow grind, their bevels are too narrow for me to maintain that correct angle with every pass on the stone. So when is a hollow-ground bevel not appropriate? Japanese tools and Western mortising chisels should not be hollow ground. Ideally, Japanese tools should be ground with a fiat bevel, to maximize support of the tip.The steel of Japanese tools can be brittle; without adequate support, a tip could fracture. Mortising chisels should be flat ground, too, or made slightly convex, for the same reason.To withstand heavy blows, their tips need to be as strong as possible.


www. American Woodworker, com october/novemser 2009

Waterstone Mat when i switched from oilstones to waterstones back in the Paleozoic era, I thought that I could say goodbye to making a big mess while sharpening. Well, not exactly. Waterstones are messy, too, when you keep their surfaces flooded with water-as you should.

I've been looking for the best method of containing the mess for years, and modem technology has finally delivered: a rubber garden paver. It's about 16" square, 3/4" thick, and made from recycled tires. Water beads up on it, and best of all, the surface is a bit rough and sticky, so stones stay put. You don't need a holder or clamps or anythlng-just your stones and the mat.

Similar material is used for floor underlay-ment for gyms, so you may be able to scrounge a mat for free, but these pavers are now available at home centers. I'll bet they'll last forever.

Source: Gardener's Supply Co., (888) 8331412, www.gardeners.com. Rubber Brick Paver Mat, #37-563, $12.95.

www. American Woodworker, com october/novemser 2009

Waterstone Maintenance

WATERSTONES ARE RENOWNED FOR CUTTING FAST, but many require regular maintenance to stay flat.This is no small thing-a fiat surface is essential for producing a straight edge and to properly remove a wire edge.

Flattening is a must-do, routine chore. How often do you have to do it? Well, ideally you'd flatten a stone each time before you use it, but that may strike you as being obsessive. Flattening after a half-dozen uses is probably more realistic. But consider this: the longer you let it go, the more dished-out a stone may become and the more work you have to do to make it flat again.

The easiest and least expensive way to flatten a waterstone is to rub it on a piece of 220 grit wet/dry sandpaper mounted on a piece of 1/4" glass. The best source for this sandpaper is an automotive supply shop. Pick up a handful of sheets, because each one is only good for two or three uses.

When you flatten, use lots of water to keep the paper from loading. You fine diamond stone under running water in a utility sink. You'll be done before you know it. If you're really nuts about this, like I am, build a support so you don't have to lean over too far.

don't have to adhere the paper to the g!ass-the water will cause the paper to stick by itself.

If you really want to get the job done in a hurry, lap your stones on a

Hone Scrapers with Diamonds a lot of folks use a stone to put the final edge on a scraper before turning its hook, but I prefer to use a diamond paddle. !t cuts faster than most stones and obviously won't develop a rut, which is always a danger when you continually run the edge of a scraper on a stone.

I use an extra-fine diamond paddle, which is roughly equivalent to a soft Arkansas oilstone or a 1000 grit waterstone. While the diamond can't make a scraper's edge quite as sharp as a very fine stone, the edge is good enough for all but the most demanding work. I lubricate the paddle with some 3-ln-One oil to float away the metal debris, so it won't clog the paddle.

To hone the scraper's edge, I position the scraper in a vise so that it's level with a small stick. Resting the paddle on the stick ensures that the scraper's edge will be exactly 90° [Photo 1). 1 also use the paddle to remove the wire edge formed by honing (Photo 2).

Source: EZE-LAP, www.eze-lap.com, (800) 843-4815, Super Fine Diamond Hone, $4.95.

octoberïnoveh ber 2009 www.AmericanWoodworker.com

Dress Those Wheels if your grinder shakes and vibrates, chances are that the wheels aren't round. Sure, they're more or less round, but they have to be perfectly round for your machine to run smoothly. For truing a wheel, you need a wheel dresser.

If your wheels are full of metai particles and have a glazed surface, you've got another problem. All that metal makes the wheel cut slower and build up heat faster-a surefire recipe for drawing the temper from a tool,To renew a wheel's surface, you need a wheel dresser.

You get the picture. A wheel dresser is a must-have accessory for any grinder. It removes material from the face of a grinding wheel the same way that a turning gouge shapes a spindle. As it cuts into the wheel, a dresser removes the high spots, making the wheel truly round. At the same time, it renews the surface by exposing fresh abrasive.

Before you dress your wheels, it's a good idea to mark them all around with a pencil so you know when all the high spots are gone. To mark a wheel, rotate it by hand and hold a pencil against it.

There's more than one type of wheel dresser, but my favorite is a T-shaped tool with a diamond face.To use it, adjust the tool rest to 90°, turn on the grinder, and gently hold the dresser against the wheel. It's that easy. You'll be amazed at the difference It makes.

Source: Woodcraft Supply, www.woodcraft.com, (800) 225-1153, Diamond Tip Wheel Dresser, #124670, $14.99.

Accurate Paring Requires A Flat Back is the back of your chisel really flat? For accurate paring, it has to be as flat as flat can be, for at least 2" to 3". Even though your chisel may look like it's OK, it probably needs to be lapped to make it truly flat.

Lapping consists of two stages: flattening and polishing. First, you flatten the back by rubbing it hard on sandpaper that's adhered to a flat surface, I've used a 1 /4" thick piece of glass, the cast iron wing of a tablesaw, or the bed of a jointer, but my favorite lapping surface Is an Inexpensive granite surface piate (see Source, below).

Start with 220 grit paper.Take a few strokes and examine the back. If it's really bad, begin lapping in earnest with 80 grit paper. On most chisels, I start with 120 grit. If the back is pretty good, stick with the 220 grit.

On your first grit, keep sanding until the scratches go all the way from corner to corner and 2"to 3" up the length of the back. This completes the flattening stage.

In the next stage, polish the back with finer and finer grits. A complete sequence is 80,120,180,220,and 320 grit paper. (You can go even further, and save wear on your stones, by using 15 micron and 5 micron 3M PSA-backed Microfinishing paper. See Sources, below.)

When you switch to a finer grit, lap In a different direction, so the scratches make a different pattern. Keep lapping on each grit until the scratches made by the previous grit disappear.

Once you've finished with 320 grit, continue lapping on your stones-assuming they're flat.

For abrasives, I prefer 3M's PSA Gold, which is available in discs or rolls at auto supply stores. It cuts faster than any other paper commonly available and doesn't require a sprayed-on adhesive.

Sources: Grizzly Industrial, www.grizzly.com, (800) 523-4777,2" x 9" x 12" Granite Plate,G9649,$19.95.

Lee Valley, www.leevalley.com, (800) 871 -8158,3M Micro-Abrasives, 15 micron, 54K93.02, $2.60 per sheet; 5 micron, 54K94.02, $3.40 per sheet.

64 www.AjneiicanWoodwoiker.com cktober/novembeh 2009

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