An improved imprinting mechanism is disclosed of the type particularly useful in document stamping machines which imprint on a document both the date and the time of receipt, and a serial number. A plurality of character wheels (30-58) is mounted for rotation on a shaft (28), each character wheel including a plurality of radially extending teeth (60, 64, 68, 72) on which the characters are located. Indexing rakes (108-116, 238-248) which engage slots located between the teeth of the character wheels to position the wheels for successive imprinting operations.