Flat Bevel

Honing with Waterstones by Leonard Lee

When it comes to sharpening, my philosophy is to get a good edge in the least time at the lowest cost. The main components in my system are a motorized grinder, a honing guide and two Japanese waterstones: an 800 grit and a 6,000 grit.

I usually start lapping chisels and plane irons on my 800-grit waterstone; then I go directly to the 6,000-grit stone. The smoother, shinier finish left by the 6,000-grit stone will show up clearly against the duller, more deeply scratched surface produced by the 800-grit stone. When you have a continuous shiny band next to the edge, stop. There may yet be a few slightly hollow areas back of the edge that arc not shiny. They will not affect the chisel's function as long as the surface is basically flat.

If a blade needs grinding (e.g., if it is nicked), a 1/4-HP double-spindle grinder is a good choice. A 1,725-rpm grinder is best, but a 3,500-rprn grinder is fine if you have the right stone for it. 1 use a Norton aluminum oxide wheel with the code 38A80H-8VBE. This is a cool-cutting, aggressive stone because it has an open structure and a soft bond, unlike the dark gray, silicon carbide tool-burners that come with most new grinders. You can find a serviceable grinder for well under $100. As well as a new stone, you should also get a good afircrmarket tool rest to replace the one that comes with the grinder.

If I intend to hone at 25*—a good angle for utility chisels—I grind the bevel 1* or 2* below that. Then when I come to hone the edge, I am honing only the front part of the bevel. I use a honing guide and an angle-setting jig. I set the chisel in the honing guide at 25° and hone a primary bevel Vl6 in. to Vfc in. wide, using the 800-grit stone. Then I lap the face (a couple of strokes) on the 6,000-grit stone to remove any burr.

I click the cam on my honing guide up a notch and hone a very narrow microbevel ('/64 in. wide is fine) 1" above the primary bevel. Again, I quickly lap the face to remove any burr.

Resharpening is easy with this system because I know the exact geometry of the edge. I set the honing guide to the primary bevel angle, go back to the 800-grit stone and strip away just enough steel to remove the rounded edge. Then I lap on the 6,000-grit stone and hone the microbevel just as before.

Guiding the edge. Using a honing guide, you can set and hold exact angles for honing both the bevel and microbevel.

Three-stone system. Lee uses an 80-grit Norton wheel to hollow-grind the bevel. For flattening and honing, he relies on 800- and 6,000-grit waterstones.

Flattening a Dished Stone

Waterstones wear quickly, but it's not difficult to restore them to flatness. Sprinkle about half a teaspoon of 80- or 120-grit silicon carbide powder on a piece of plate glass. Add just enough water to make a slurry and then lap the 800-grit stone. Once the 800-grit stone is flat, wash it free of loose abrasive and then rub it against the 6,000-grit stone (using water as a lubricant) to flatten the finer stone. ▲

Leonard Lee is the author of The Complete Guide to Sharpening (1995, Taunton Press, Newtown, CT 06470).

Pros

Only two stones are needed; honing guide allows for precise, repeat-able honing of primary bevel and microbevel.

Cons

Waterstones need regular conditioning to maintain flatness.

Components and costs *

♦ Norton 6-in. x 1-in., 80-grit grinding wheel, code 38A80H-8VBE $25

♦ 800-grit waterstone,

♦ 6,000-grit waterstone, '/2 in. x 2V2 in. x 7 in. $23

♦ Grinding jig and tool rest

♦ Veritas honing guide and angle setter $33

Total cost $228

Optional equipment

♦ Sharpening station for waterstones $45

m Approximate costs, based on current mail-order prices.

Sharpening with

India and Arkansas Stones by William Neptune

When I sharpen chisels and plane irons, I rely primarily on a bench grinder and on several oilstones and strops. While I've experimented with waterstones, ceramic stones and even diamond abrasives, I keep coming back to oilstones to hone the bevel. It's true that oilstones don't cut as quickly as water-stones, but this isn't a problem when you're honing a hollow-ground bevel because there's much less metal to remove.

I used to begin lapping the back on the coarse (100-grit) side of my combination coarse/fine India stone. Now I like to do my initial lapping on a coarse diamond stone. The 12-in. precision diamond stones from DMT are great for lapping. I still finish flattening the back on the fine side of mv combination India stone.

Once the back is flat, I go to rhc bench grinder and hollow-grind the bevel. (Sec photo, right.) I use the hollow-ground bevel to register the honing angle on my oilstones. Honing at the same angle as the grind will leave two narrow bands of shinier, smoother steel—one along the top of the bevel and one along the bottom.

I start honing the bevel on the fine India stone. I dribble a couple of drops of Marvel Mystery Oil (other machine oil will also work well) on the stone and spread it out with my fingers. The oil keeps the abraded steel dust in suspension, so that it can be wiped clean periodically, before it clogs the stone.

Initially, I move the chisel or plane iron in small circles, keeping near the edges of the stone to avoid hollowing out the middle. After £ a couple of minutes, I finish up with several r straight strokes on the bevel and back. I've

* found that "straightening out the scratches" ; like this yields a more durable edge.

After the fine India, I go to my hard white

* Arkansas stone and repeat the same sequence: L circular motion first, then a few straight

1 strokes on bevel and back. If you're new to ~ sharpening, it will take some time to gain the

2 steadiness and feel required for freehand hon-\ ing. But with practice, this freehand proficients cy will come in handy when you have to £ sharpen gouges, carving tools and other edge £ tools that can't be held in a honing guide.

Though it's possible to finish the edge by s honing on even finer oilstones, at this stage I < usually choose to strop the bevel and back for £ that extra measure of sharpness. To make a

Wheel work. Hollow-grinding creates a concave lyevel that minimizes the amount of metal you need to remove when honing.

Strops, stones and wheels. Neptune's sharpening system logins with a Baldor grinder and ends with super-fine oilstones and leather strops.

strop, I simply glue a length of smooth, flat leather to a base of ^/4-in.-thick MDF. I charge the strop with abrasive compound, spreading the compound over and into the leather surface.

When stropping, I keep the bevel's "flats" in contact with the strop, and use a straight pull stroke. Tipping the edge into the abrasive tends to depress the leather slightly; this will create a curved or "dubbed" microbevel, which you don't want. A

Will Neptune Woodworker

Will Neptune makes furniture and teaches woodworking at Boston's well-known North Bennet St. School.

Pros

Oilstones wear slowly and evenly; hollow-grinding removes nicks quickly and minimizes honing time.

Cons

It takes practice to hone freehand, without a honing guide; oilstones don't cut aggressively.

Components and costs *

♦ Baldor 7-in. low-speed (1,750-rpm) grinder with 80- and 120-grit wheels

$280

♦ Norton India combination coarse/fine oilstone $20

♦ Norton hard white Arkansas "select" stone $60

♦ Leather strop $2 to $5 Available from shoe repair shops or leather crafters.

♦ White rouge abrasive compound for strop 55

Total cost: $370

Optional equipment

♦ 325-grit DMT precision diamond stone, 12 in. $80

♦ Approximate casts, based on current mail-order prices.

Lapping and Sharpening Plates by Barrt/ Biesattz

The system of lapping plates and abrasive compounds from Harris Tools has worked very well in our shop. After nearly two years of constant use, the lapping plates are still flat, and we've only had to replace one 1.5-ouncc bottle of silicon carbide abrasive.

The basic sharpening system consists of two 3-in. by 8-in. cast-iron plates (one grooved and one smooth), an aluminum holding tray and four different abrasive compounds. Each plate is ground flat on both sides—to a tolerance of 0.0002 in. The steel used to make the plates is just soft enough so that abrasive particles will embed themselves in the lapping surface. When you lap or sharpen, the tool bears on the embedded particles, not on the plate itself. When properly "chargcd" with abrasive, the plates cut quickly and don't wear. Only one abrasive grade can be used on each lapping surface, but the two plates provide a total of four surfaces on which to sharpen. Additional plates arc available.

With a new chisel or plane iron, 1 first flatten the back on the grooved plate, working on the coarsest side—the one charged with 280-grit silicon carbide. The grooves on this plate help to carry away the extra swarf (abraded metal) made by the coarser particles. I move from the 280-grit side to the 600-grit side, and finish lapping the back on the smooth plate charged with 10-micron diamonds. I don't look for a polish on the back, just for a uniform gray color that indicates a flat surface.

To sharpen the bevel, I can go all the way back to 280 grit if the edge is extremely dull. I still use our motorized grinder to grind out nicks, but I don't like to hollow-grind chisels or plane irons because it leaves less metal behind the cutting edge. We often need the extra strength of a flat bevel when chopping into tropical hardwoods.

Honing the edge on the 10-micron plate will give me an edge that's sharp enough for most work. For a sharper edge, I hone and back off the blade on the 5-micron side of the smooth lapping plate. Harris also offers an even finer diamond paste, but I haven't had the need to use it yet. (Sec Optional Equipment, right.)

The Harris system docs require some special treatment to perform perfectly. Periodically it's necessary to "recharge" a lapping plate, when abrasive particles work free of the surface or become worn.

Lapping the back. Working on the coarse grooved plate, Biesanz applies even pressure over the back of the chisel to make it flat.

Plates, powder and diamond paste.

Charging the flat iron plates with abrasives makes them work like sharpening stones. The syringes hold diamond paste; silicon carbide powder comes in vials.

It's important to protect each lapping surface from being contaminated with other grits. When you switch from one grit lapping surface to another, you have to wipe the blade clean so you don't carry a coarser grit onto a finer abrasive surface. And the plates should be stored so lapping surfaces don't contact each other. These precautions haven't caused any problems in our shop. ▲

Barry Biesanz runs a professional woodshop in Belo Horizonte, Costa Rica.

Pros

No motorized grinder required; lapping plates will stay flat indefinitely.

Cons

Initial expense is high; plates must be stored carefully to avoid contamination.

Components and costs *

Harris Lapping System:

♦ Two 3-in. x 8-in. lapping plates-Grooved $79 Smooth 56 J

♦ Aluminum holding tray

♦ Silicon carbide abrasive— 280 grit, 1.5 oz. $3

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Responses

  • markus
    How to use harris tools lapping and sharpening system?
    6 years ago

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