Yes, and it is worth knowing how: besides replacing a seized bearing, fitting one of a different diameter changes how deep the bit cuts, which turns one profile cutter into several.
The bearing on a piloted bit is held by a small screw through its center, and it is a standard part.
Doing it
Hold the bit by the shank in soft jaws or a cloth. Undo the screw — some are hex, some Torx — lift off the bearing and any shim, fit the new one, and tighten firmly. Check the bearing still spins freely afterwards, because an overtightened screw or a trapped shim locks it.
Why you would
Two reasons. The first is a seized bearing, which happens: resin and dust get in, the bearing stops turning, and instead of rolling along the workpiece it burnishes a black line into it.
The second is more interesting. The bearing sets how much of the cutter is exposed. A smaller bearing on the same bit cuts deeper; a larger one cuts a partial profile. A rebate bit with a set of bearings cuts a whole range of rebate widths from one cutter, and the same trick turns a single round-over into several partial profiles.
Keep them clean
A bearing that is dragging is on its way to seizing. Solvent, then a drop of light oil, and never grease — grease traps dust.
Last reviewed 2026-08-12