The key-way machine is used for the purpose of cutting a slot or a key-way in any thick piece of metal, such as a pulley. The machine is not complicated and its operation requires very little skill. A cutter resembling a very coarse file makes the proper width of cut and is held to the work by the machine.

The operation of a slotter is similar to that of a shaper with the difference that as the ram works vertically instead of horizontally, the tool cuts on the down stroke, and the ram is counterbalanced to return easily. The slotter is used on irregular shapes and especially on all kinds of heavy work. Such work requires only an ordinary machinist, although specialists are sometimes employed.