A tool which imparts a reciprocating or backwards and forwards motion to a pinion, or a tool for polishing a pivot or pinion leaves. In the pivot-polishing version of this tool the polisher, which is either a burnisher or soft-metal polisher charged with a polishing compound, is worked to and fro, while at the same time a rotary motion is imparted to the pivot. For polishing pinion leaves, the pinion is moved axially back and forth over a charged polisher which can be a rotating disc.