Popular Woodworking 2007-04 № 161, страница 28

SHARPENING A CRESTED BLADE

The motion is side to side and in an arc. At the beginning of the arc, my finger pressure is on the right corner of the plane blade.

As I move the tool to the right, I shift my finger pressure to the center.

At the end of the arc, I sh ift my finger pressure to the left corner of the blade.

Sharpening the cannel of a gouge involves rolling the tool as you move it along the sandpaper. Begin with the cannel contacting the sandpaper on one end (left). As you move the tool along the paper, roll the gouge (right) so that at the end of the stroke you have the opposite corner of the cannel touching the paper.

to side along the paper. To work the cannel, use various grits of sandpaper applied to dowels.

Crested Plane Blades

Jack and smooth plane blades are crested. In other words, the cutting edge is an arc that looks like a fingernail. This is easy to do on sandpaper. In this case, I shape the edge before flattening the back. Place the blade on its bezel and find the correct angle by lifting the end until the cutting edge makes contact.

You are going to use a side-to-side motion, but it will also be arced. Begin on one corner applying pressure there with the fingers of one hand. As you slide along the edge, gradually shift the pressure to your other hand, so that by the time you reach the other corner the weight is all on those fingers. By moving the blade along an arc and shifting the weight, you will abrade more metal from the corners. Keep up this motion and the blade becomes crested. How much you crest the cutting edge depends on the plane's purpose.

Once the cutting edge is crested, flatten the back of the plane blade as you would a chisel. As you proceed through increas

ingly finer grits, return to the bezel and work it in conjunction with the back.

The Knife-edge Tools

Many tools have a knife edge. A knife edge is most desirable when a tool cuts down into wood and back out again. Most knife-edge tools are used for shaping and other fairly rough work. An ax, adze and scorp (inshave) are examples of knife-edge tools. A drawknife is also a knife edge, but is a slightly different matter. I do not use the lapping plate for knife-edge tools. Instead, I use wood blocks or dowels with paper adhered to them.

The two sides of a knife edge are symmetrical. Although they are slightly rounded, their shape only defines the angle of the cutting edge. Our definition of sharp still applies, for at the very cutting edge the surfaces are still flattened and polished.

Sharpen an Ax

The ax is the simplest knife-edge tool. So, let's start here. I adhere several grits of paper to ³/4"-thick hardwood blocks about 3" by 4". I have a small hand with stubby fingers. If you have a big hand, use a block that fits you comfortably.

42 Popular Woodworking April 2007