Almost everything that ends a tool's day on site is mechanical. A switch can fail, a cord can be cut, a chuck can lock up — but the single most common cause of a power tool dying mid-job is a worn pair of carbon brushes. The fix is fifteen minutes and a few pounds; the lost time when the spare isn't in the van is anything from an afternoon to a full day.
The economics make the case on their own. A pair of OEM-grade brushes for a Makita or DeWalt sits in single-figure pounds. An hour of a joiner's or electrician's time on site sits well into double figures. Most tradespeople we sell to keep one pair per regular tool in the case and a generic spare in the van — it has saved them more days of work than they remember.
Which brushes to keep depends on the kit. The tools that work brushes hardest are angle grinders, mitre saws, SDS hammers and the corded drills that do anchor and substrate work. The most-bought van stock in that order, in our experience, is Makita carbon brushes (especially for 9558NB grinders and HR-series SDS hammers), DeWalt brushes (mitre saws and impact drivers), Bosch brushes (Professional Blue range), and Hitachi and HiKOKI brushes. The wider carbon brushes hub covers the rest of the brands.
Fitting is straightforward at the kerbside. Two screw-in caps on the side of the motor housing release the springs and old brushes; the new pair drops in the same way. Thirty seconds of no-load running seats the new face against the commutator and you're back at work.
The single best habit is to keep the original brushes — once they've worn down a third — as a reference for re-ordering. Dimensions and terminal style are stamped or visible on the side. With those in hand, the right replacement is a one-click order from the tool parts hub.