Monotype lapping machine, used by Monotype Corporation

The Monotype lapping machine is the final stage in the matrix making process. Numerous matrices are cued up in a channel in the machine to be planed on two sides by two spinning diamond discs. They are then put through the machine again in order to plane the other two sides. Certain parts of the machine are lubricated by oil flowing over them. Each matrix is then checked to see that it fits exactly into a hand-held gauge. This ensures that they fit perfectly next to other matrices when an entire fount is arranged in a matrix case.

The planing of matrices to the correct final size can be done by hand, but the machine is still used when there are multiple matrices to be done. There are, for example, 255 matrices in a standard matrix case.

The machine occupies a room of its own at The Type Archive. It is the only one of its kind in the world.