Saturday, March 22, 2008
Lettercarving, Part II
Lettercarving is a great way to enhance your work. To carve a letter "O", or any curve, you must know in which direction to slice the wood in order to avoid tearout. The diagram shows you the direction of the cut on both the outside and inside curves. The horizontal lines represent wood grain, the dotted line is the stop cut, and the arrows show the direction in which to slide the chisel or gouge. When you slice in the correct direction, the wood fibers are continually supported ahead of the cut. If you were to cut in the opposite direction, the wood fibers ahead of the cut are too short to support the fibers you are slicing, resulting in tearout.
In the diagram, the points at which two arrows meet are at the top, bottom, and sides and show where you need to switch the direction of your cut. You can start cutting at any of these junctures and stop when you get to the next one. You will need to feather the junctures with very thin slices in order to obtain a smooth transition.
When cutting a curve, the outside wall is concave, and is therefore carved with a gouge, while the inside wall is convex and is carved with a straight chisel (which is always bevel up).
A gouge requires that you hold the handle at a steeper angle in relation to your work surface. A straight chisel is held at 20 degrees, while a gouge is held at 40 degrees. A gouge held at a lower angle will result in a wider side wall that will reach beyond the middle of the letter. As with carving a straight letter in part I, keep the cutting edge of both the gouge and chisel at 45 degrees to your pencil line.
Where the letter is thinner, in this case the top and bottom, the depth of cut will be more shallow, since you are always maintaining the same compound angle with both chisel and gouge.
Once you understand in which direction to cut, based on the grain, you can apply this technique to any letter or design that has curves.
I used a 12mm straight chisel and a 12mm gouge with a 3 sweep to cut the letter.