Router Bit FAQ

How do carbide router bits get damaged?

Router bits can break, and carbide can snap from vibration and bouncy chattering. The first defense against breaking starts by using a shorter length whenever possible. Use a bit just as long as needed and no longer. If it flexes while pushing too hard, the stress can result in chipped carbide. Steel can flex and return to shape, but aggressively routing dense hardwood can crack brittle carbide or compromise its attachment.

Narrow, long bits are prone to chipping and breaking, and typically come minus the benefit of guarantee. For example, this straight plunge bit with a half inch shank, a 1/2 inch cutting dia., and a 2 in. long flute is likely to flex.

On a 1/4 inch shank with a 1/4 in. cutting dia., even a 1/2 in. one risks cracking. If you need extended length, use a wider one that has a better chance of avoiding damage from flexing. A shank size of 1/4 inch is quite flexible, but a fatter one is stiffer.

If you notice a wobble or noisy buzz, stop. Locate the source of vibration and reduce it to a calm hum. Stabilize the work. In hard materials, go easy instead of hogging. The harder you are routing, the more the binder wears. Routing by consistently sweeping one way is wiser than abruptly churning back and forth in choppy, unpredictable jerks. As the grip is tested by the strain of such usage, it might slip. Impact can crack carbide. Try to avoid hitting knots or embedded metal fragments.

Ball bearing bits

A ball bearing guide limits the depth of cut by rolling along a template. It is a separate part, most often installed at the end. It must roll independently. It may extend on top or be found below the flutes, which are the sharp parts of a router bit. Once firmly pressed in, the pilot engages the stock. It should not turn with the bit; that defeats its purpose. Roll it to feel for any hesitation. If it is so dirty it won't roll, it will smudge or singe the surface.

Clean the bearing by simply flicking or brushing away clumps so it won't bounce or leave a repeating pattern on the wood. If you are cleaning router bits in fairly new condition, you do not want to let solvent strip out the grease in the ball bearings. To loosen a stiff bearing, squirt on one miserly drop of WD-40, work it back and forth and wipe it all off. When a stuck bearing is stubbornly frozen or rusted, the internal lubricant is dried up. If it is hopelessly bad, you might let WD-40 penetrate the seized parts, and wish for a partial loosening. It is a temporary fix in desperation to get a job done. If it works, it probably could have been fixed by a toothbrush and elbow grease alone.

In a worst case scenario, disassembling and then replacing a bearing by another one of the same size is still less trouble than obtaining a whole new bit. Installing bit bearings is not really a chore if they have good, undamaged cap screws. Remove an end bearing by using an Allen wrench to unscrew its cap. If the head of a screw is too damaged, vise grips could probably still take it off. To remove an upper, shank mounted one, unscrew the set screw on the retaining collar. Then slide the parts together off the shaft.

After a flush trim bit is reground several times, it may get smaller than the guide. While trimming laminates, it might leave unwanted ridges. You could file off the excess plastic laminate, or simply replace a bearing by a new, smaller .492 inch one.

Delrin or white nylon bearings are slightly softer to avoid marring solid surface or plastic. They have a few specialized uses; primarily for routing sink bowls.

A solid carbide flush trim bit also cuts on the side, and is guided along the stock, but it just has a simple static pilot which is a short smooth section near the tip.

Homemade storage box

A storage case protects bits from rattling around and damaging each other. You can use free recycled materials for a simple but effective homemade box. It is as easy as fitting a block of Styrofoam in a shoe box. Poke each shaft into it. Space them apart so none touch. Toss in a packet of silica gel to discourage rust. For straight bits, you can craft some caps out of a plastic tube cut in short pieces.

For storing or shipping, you can warm up some soy plastic to dip the heads. When you are ready to route, carefully cut the side of the seal and manually pull it off. Wipe off the thin film of oil with alcohol before using it.