Читать книгу The Uke Book Illustrated - John Weissenrieder - Страница 10

Sharp tools are paramount to precise work, giving the craftsperson superior control. They are much more predictable and require less force to use, and therefore are safer. A well-sharpened plane is said to “sing” when cutting, and indeed there is a certain inherent pleasure in using a well-honed blade, be it a plane, chisel, knife, scraper, or saw. It’s well worth the effort to learn how to prepare your edge tools for optimum cutting.

With a little practice and minimal expense, professional results can be achieved at home using abrasive papers on plate glass (or an extremely flat piece of granite or other stone) and a simple honing guide. The abrasive papers will adhere to the flat surface when wetted (and they are to be used with water) and can be easily changed when worn out or when it’s time to change grits.

The edge is where the two surfaces meet. A “flat” and a “bevel” are called a single bevel. If both sides are beveled, it’s called a double bevel. Sharpening can be broken down into two phases: shaping the blade and polishing its surfaces.

Shaping is done using coarse abrasives (220-400 grit). The goal now is to establish a perfectly flat back surface and a correct angle to the bevel side; 30° is typical. Scratches from the abrasives are still okay at this stage; they’ll gradually be polished out, leaving a sharp edge.

Next, the coarse scratches are removed using a fine grit (1000) and then the blade is polished using a super-fine grit (2000-4000). The resulting edge should have a mirror finish. Seeing as it’s not necessary to have the whole blade shining like a mirror (1.5mm at the cutting edge is sufficient), a micro bevel can be created.

Changing the sharpening angle slightly ½ degree is sufficient) creates a micro bevel, which doesn’t affect the overall flatness of the bevel or blade back in a significant way. High-quality honing guides have a feature that allows for the micro adjustment of the angle for the final polishing. Otherwise it is easy to improvise a guide for the micro bevel: simply shim up by about 1.5mm the back support (or roller) of the honing guide.

Many honing guides don’t accommodate knives, so the bevel side(s) will need to be sharpened by hand. The back is lapped flat using the same technique as used for a chisel or plane blade, without the use of any honing guide; but the bevel is most often done freehand. Be as steady as possible, avoiding rounding over the bevel at all costs.