Router Bits

Carbide-tipped router bits offer two advantages; heat resistance and long edge lives as compared with steel. However, carbide router bits are brittle and prone to chipping, and can be expensive, which is the reason that most router bits are tipped with carbide, rather than being made of solid carbide. Carbide-tipped router bits may last up to 20 times longer than HSS router bits.

High-speed steel (HSS) router bits are well suited for occasional work and are less expensive than carbide bits. However, HSS router bits dull relatively quickly and need to be re-sharpened to prevent them from burning workpiece surfaces. Some HSS router bits are coated with titanium nitride for long life, but the coating eventually wears off.

There are two types of router bits: pilot and nonpilot.

Pilot bits have ball bearings that keep the router bits at fixed cutting distances from the edge of the workpiece. Nonpilot bits have no ball bearings, and work in conjunction with fences or jigs that control cutting paths.

When using pilot bits, the bearing should rotate freely, and pressure should be applied to keep the bearing pressed against the workpiece. However, care must be taken so that the bit is not pushed too hard.

Some router bits are designed with chip-limiting characteristics. Chip-limiting router bits have extra body mass that extends further back to reduce the amount of material that can be fed into the bit's flutes. This reduces the chance of over-feeding the bit, which, in turn, reduces the chance of the router bit kicking back.

Router bits commonly are available in two sizes: 0.250 in. and 0.500 in., referring to shank diameters. Large router bits typically use collets that accept either shank size, and most small routers, because of motor size, handle only 0.250-in. bits.

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