Popular Woodworking 2007-04 № 161, страница 25

These were my criteria. I had to do more than just hone an edge. I had to be able to reshape an entire blade in very short order. My classrooms were full of unusable tools and I could not spend a lot of time on each one. A lot of chairmaking tools have curved blades, and also use both chisel- and knife-edge profiles. So, my eventual solution would have to be versatile. Finally, I would need supplies that were easy to find and provide. Hosts were not going to buy expensive equipment just for me.

The Answer: Sandpaper

Three things I could find in any host's work space were sandpaper, a flat surface and small pieces of wood. This was my answer. It was not so much a ""eureka" moment as it may appear. I had already been using sandpaper on plate glass for a decade to lap plane soles. I was really taking a process I already used and expanding on it.

Sandpaper sharpening solved my problem. It also had an added benefit. It is so easy and simple that once shown, my students got it and were able to sharpen their own tools. Other advantages are that you will never again burn an edge, and you will be able to use this system to sharpen just about anything, from your best plane to a lawn mower blade.

The primary piece of equipment and the one that will probably cost the most (but not much) is a suitable hard, flat surface. In the beginning I used plate glass, as glass is easy to find. However, it breaks. While no one was ever hurt, I worried. Today, I use 1/2"-thick aluminum plates that I bought from a metal dealer. You could also use a piece of granite countertop. Whatever you select, it should be long enough to hold numerous strips of sandpaper of various grits.

The actual sharpening is done

with sandpaper. I prefer aluminum oxide, as it seems to hold up best. You can adhere the paper to the lapping plate with spray adhesive, or purchase self-adhering rolls. I do both. Purchase the rolls from a sandpaper catalog and the adhesive at a hardware store.

You will need a variety of grits. We use #80, #120, #180, #220, #330, #650, #1,000 and #1,500. The last three grits are wet-and-dry sandpaper available from automotive-supply dealers. Do not confuse these sandpaper grits with waterstone grits. They are not the same measurement.

You will also want to have on hand a stiff brush for keeping your paper clean of loose grit. I use a wallpaper brush. Single-edge razors and a holder help remove worn-out paper. Paint thinner dissolves any leftover adhesive. These are all available at a paint store. Finally, you will need a variety of hardwood ³/4" blocks of a size that will fit comfortably in your hand. Pieces of dowel of various diameters about 4" long complete the equipment.

Setting up your sandpaper system depends on your needs. I keep a strip of #80-, #120- and #330-grit paper on one side of the plate and the wet-and-dry papers

on the other. You will be more able to plan your own setup by reading on.

Know What a Sharp Edge Is

A lot of the problems woodworkers have with sharpening stem from not knowing, or not being able to envision, what they are trying to accomplish. A sharp edge is simply two flat, polished surfaces intersecting at an angle that will cut wood cleanly. While that is a simple definition, it is very demanding, in that anything less is not sharp. The definition permits no shortcuts, no half measures.

How to proceed depends on whether you are starting with a new, factory-ground edge; an old beat-up, nicked and rusted edge; or a well-maintained edge that merely needs to be honed. It will also depend on whether the tool has a chisel edge or a knife edge. As you can see, this requires some judgment. Sharpening is not a rote process of so many strokes of this surface, followed by so many strokes on another. You need to combine whatever variety of processes your tool needs to achieve our definition.

Factories usually create an edge by coarsely grinding the two surfaces. This is the condition

of many cutting edges on newly purchased tools. The grinding leaves behind a series of parallel scratches. If you were to magnify these scratches, each one is a tiny furrow in the metal. Where each furrow intersects the cutting edge it creates a dip. Under magnification, this row of dips looks like the teeth on a saw. Imagine trying to push a saw blade across a piece of wood. It would take a lot of force and the result would be a row of scratches. That is what happens if you try to use a factory edge.

A beat-up edge, as you frequently find on secondhand tools, usually has nicks and rust. A nick is similar to a furrow as described above, but nicks are not evenly spaced and are frequently bigger. Rust will pit the steel, and these pits too, when they intersect the cutting edge, act like the furrows. They leave scratches and require more force to work the tool.

Furrows, nicks and pits need to be removed. This is the reason for the #80-grit sandpaper in my system. It will cut metal fast.

Sharpen a Chisel

Let's start on a chisel edge as it is the one most woodworkers recognize. Remember our definition. An edge is two flat, polished sur-

You don't need expensive equipment to get a sharp edge. Here you can see my aluminum plates, sandpaper and small scraps of wood that allow me to sharpen all of my tools. The razor blades, utility knife and brush round out the equipment needs.

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