A plurality of outwardly and radially extending font segment support arms are coupled to a central hub which is rotated to sequentially present the letters formed upon the segments to an optical imaging station which selectively projects optical images of the letters upon a photosensitive medium. Vertical shoulder portions are precision machined upon outer portions of the radially extending support members for precisely positioning the arcuate character tracks on the segments with respect to the imaging station. Horizontal plates are affixed to the radially extending support members to support the segments against gravity and centrifugal force is employed to precisely seat the segments against the vertically oriented shoulder portions upon rotation of the hub.