Abstract: A machine for coding or duplicating a pattern of bits onto a key blank employs a locator block which forms reference slots for receiving a key to be duplicated. A template having a matrix of openings which correspond to possible pre-established bit locations is positioned in registration with the key receiving slots. A depth gauge is employed so that a guide selectively seated in a bit defining cut-out of the pattern key indicates the correct incremental depth of the bit to be duplicated. A cutter having a preestablished relationship to the depth gauge guide is employed to obtain the correct cutting depths for the key blank bits.