Bearings are the second most common reason a power tool ends up at the bench, behind only worn brushes. The first sign of a failing bearing is rarely visual — it is auditory. A rising whine on no-load running, a faint rumble under load, and a small wobble at the spindle or disc when the tool is spun by hand are the giveaway signs.
Power tool bearings are almost always standard sealed deep-groove ball bearings, the same kind used in electric motors, gearboxes and bicycle hubs. They are specified by three numbers: inner diameter, outer diameter and width, all in millimetres. These three numbers are usually printed or stamped on the steel seal of the original bearing — a typical small-tool bearing reads something like “608ZZ” or “6201-2RS”, where 6 is the bearing family, 08 is the bore (8mm), and the suffix indicates the seal type.
Once you have the size, ordering is straightforward. We stock the common sizes for power-tool work under bearings and mechanical components. The seal type matters: ZZ (metal shields) is the standard for power tool work, 2RS (rubber seals) gives better dust protection but slightly more drag.
Replacement on most power tools needs a small bearing puller and a few minutes of patience. The bearing pulls off the armature shaft with the puller, the new one slides on with a tap from a soft mallet against the inner race only — never against the outer race, which damages the new bearing immediately. On angle grinders and SDS hammers, the spindle bearings are usually a clean swap; on the armature bearings, the brushes have to come out first.
If you have the tool apart for bearings, replace the brushes at the same time. It is a tiny additional cost and saves you stripping the tool twice. See carbon brushes for power tools for direct fitments. For the wider list of power tool wear parts, the tool parts hub is the fastest route.