A router is only as good as the bit it turns. The quality of the cuts you make will depend largely on the quality of the bits you use.
Recent developments in bit-making technology have increased the likelihood that your bits will begin sharp and stay sharp. And they have expanded the choices available to woodworkers, although those extra options can sometimes seem more confusing than helpful.
The first decision involves choosing the appropriate material for the bit. Most cutters are made from either high-speed steel (HSS) or high-speed steel with carbide cutting edges. HSS bits are adequate for working with softwood, but they will not stand up well to long-term use in dense hardwood. While carbide-tipped bits are more expensive and prone to chipping, they stay sharp longer and cut more easily through harder wood.
Many experts argue that machined bits are better made than cast router bits, and double-fluted bits cut more smoothly than single-fluted cutters. Quality is, of course, important. Before buying a bit, make sure the shank is perfectly straight. A bit that does not spin true will shudder, producing a rough, imprecise cut. On carbide-tipped bits, also inspect the brazing
bond between the cutting edge and the shank. A bit with an uneven bond may fly apart under the stress of a cut. Other features are worth considering. For example, a bit boasting a nonstick coating like Teflon™ will take longer to become gummed up with pitch. As shown on page 25, you can also choose between piloted and non-piloted bits, cutters that feature anti-kick – back characteristics, and bits with spiral cutters.
Bits with different shank sizes perform different jobs. To shape an edge with a hand-held router, for example, a ‘/4-inch bit is usually appropriate. If you are using a bit with a ‘/2-inch-diameter shank, mounting the router in a table will yield the best results. Large bits can be difficult to control in a hand-held router. Instead of using one large bit, however, you can make consecutive passes with two smaller bits.
This chapter illustrates several of the more popular bit profiles and shows the shape each type cuts in wood. Edgeforming bits arc presented beginning on page 26, grooving bits arc shown on page 28, and router table bits follow on page 30. Useful tips on sharpening and maintaining bits are provided starting on page 32.
The staircase handrail shown at left was shaped by making two cuts with different piloted bits mounted in a table-mounted router. A handrail bit shaped the bottom portion of the piece and a table-and-handrail cutter rounded over the top.