Let's Have a Bit of Order
Shopping for power-carving bits, you learn one thing quickly: They come in astonishing variety. Your eyes may glaze over as you survey the array of types, shapes, and sizes. Are you facing a fathomless jumble? Not at all—there is order to the world of carving.
A convenient way to classify power-carving cutters and grinders is by useroughing, carving, and detailing. Roughing out a carving, for instance, calls for quickly grinding away a lot of wood with little regard for surface finish. Forming feathers or other fine details, though, requires a more precise touch.
To select the proper type of bit, consider how much wood you want to remove, how fast you want to take it off, and how smooth you want the surface to be. We look at some of the popular choices in bits on the following pages.
As to size and shape, just pick the bit that best fits the job at hand. Some of the shapes you ll find are shown above.
Roughing and Shaping Bits
- Karbide Kutzall. For many power carvers, this is the first choice for roughing a figure from a solid block or bandsawn blank. Described as a structured-tooth, tungsten-carbide cutting tool, a Kutzall looks a little like a magnet that s been dipped into iron filings, shown below (1). with a big, silver cutter. Kutzalls come in two grades, silver and gold (2). Both leave a striated surface, but it s more pronounced with the coarser silver one. (Some carvers favor this texture for decoy heads and the like.) For fastest wood removal, go with a big, silver cutter.
- Steel or carbide burrs. These fluted bits, shown at below, cut like a file. The single-cut burr s cutting edges wrap in one direction around the body. Flutes on double-cut ones cross at an angle. Many carvers like extra-coarse, double-cut burrs, such as the Pfingst SGX Super-Carbide Cutter (4). These bits pare away wood much faster than other burrs, yet leave a smooth surface. They come in several shapes and sizes.for carbide cutters. A burr may be solid steel or may have a solid carbide head bonded to a steel shaft. Though costly, carbide burrs will cut a lot of wood before they dull. Many dealers offer resharpening and reconditioning for carbide cutters.
- Cross-cut cutters. Carvers call these bits stump cutters. Made of high-speed steel, a stump cutter looks pretty much like a single-cut burr, except the cutting edges have been crosscut to create orderly rows of teeth around the bit s body, as shown below (5). Stump cutters leave a smooth, sometimes slightly ridged surface. They re available in coarse, fine, or extra fine. A coarse one can work an area down quickly. The finer cutters are suited to more precise work.
- Ruby carvers. These popular abrasive bits, below (6), take their name from the mineral particles bonded to the steel body. Over the years, these bits practically have become the power carver s staple tool for refining forms and establishing features. Available in two grits and a variety of shapes and sizes, ruby carvers cut at a medium rate and leave a sanded-looking surface.
- Diamond points. Here s another chance to carve with precious stones. Many carvers consider diamond points, such as the examples shown below (7), to be the crown jewels of carving. Often thought of as finishing tools or detail-carving bits, there s really no reason diamond points couldn't be used at almost any carving stage. As long as the diamond chips remain bonded to the base material, a diamond bit should be able to cut wood practically forever. Compared to ruby carvers, diamond instruments cut faster, last longer, leave a smoother surface, and, as you might expect, cost more. (But not, surprisingly, a lot more in many cases. Diamond points are available in a great array of styles and sizes, too.
- Texturing stones. Whether fish or fowl (or anything else), your work will look more realistic with the correct surface textures. That s where abrasive stones come into play. But determining which ones to use often calls for some experimentation. Your dealer will have a colorful batch of stones to choose from—pink, green, white, and blue are usual. Each color denotes a different grit and hardness. For the stones shown below (8), white is the finest grit, thus the slowest cutting. Where the colors rank in relation to each other seems to vary among manufacturers; ask your dealer for specific advice. Selecting texturing stones isn t a precise science. Try different combinations of color and shape until you find the ones that give the look you want. Because stones only cost a buck or two each, you can afford to fool around with a lot of them.
Cleaning, Sizing & Purchasing
When cutting performance declines, don t assume that your bit is worn out. More likely, it s just loaded up with wood fibers and resin. Cleaning probably will revive it.stones. For diamond points, buy an inexpensive dressing stone. For longer bit life, store them with their shanks standing in holes drilled in a block of wood.
A brass-bristle brush, about the size of a toothbrush, cleans light buildups from everything except stones. Heavier buildup usually yields to oven cleaner. To quickly clean a clogged Kutzall, blast it for a few seconds with your propane torch, then brush away the burnt wood.
A crepe sanding-belt cleaner works fine on stones. For diamond points, buy an inexpensive dressing stone. For longer bit life, store them with their shanks standing in holes drilled in a block of wood.
Sizing things up
When buying bits from a catalog, you may find the diameter designated by a three-digit ISO number, such as 018 or 070. To convert that number to millimeters, insert a decimal point between the second and third digit. Thus, the 018 bit in the example is 1.8 mm diameter and the 070 is 7.0 mm.
Shanks are 3⁄32 " for most bits, 1⁄8 " for some. Big carbide bits and Kutzalls have 1⁄4 " shanks. Before buying one of these biggies, confirm whether your rotary hand tool or flexible-shaft handpiece will accept a 1⁄4 " collect. Most handpieces will, most rotary hand tools won't.
If you can t find the bits you need locally, try these mail-order suppliers. Call or write for a catalog.
Christian J. Hummul P.O. Box 522 Nescopeck, PA 18635 800/468-7070
Wood Carvers Supply, Inc. P.O. Box 7500 Englewood, FL 34295-7500 800/284-6229
The Woodcraft Shop 2724 State St. Bettendorf, IA 52722 800/397-2278