Optical center punch

Claim 1

AN INSTRUMENT FOR MARKING A POINT ON THE SURFACE OF A WORK PIECE, COMPRISING A UNITARY SUPPORT HAVING A FACE ADAPTED TO LIE UPON THE WORK SURFACE, A LONGITUDINAL BORE EXTENDING THROUGH THE SUPPORT PERPENDICULAR TO ITS FACE, SAID BORE HAVING AN AXIS IN FIXED SPACE RELATION WITH RESPECT TO THE SUPPORT, AN OPTICAL MEMBER ADAPTED TO BE REMOVABLY RECEIVED IN THE SUPPORT BORE AND ROTATABLE ON THE AXIS OF THE BORE, A RETICLE CARRIED BY THE MEMBER PROXIMATE TO THE WORK SURFACE, SAID MEMBER HAVING LIGHT ADMISSION MEANS COMPRISING A REENTRANT CIRCUMFERENTIAL NOTCH TO ILLUMINATE THE RETICLE AND RESTRICTED SIGHT OPENING TO ENABLE AN OPERATOR TO SIGHT SIMULTANEOUSLY ON THE RETICLE AND ON THE SURFACE OF THE WORK PIECE IN ORDER TO ALIGN THE RETICLE AND SUPPORT WITH A PREDETERMINED LOCUS POINT ON THE WORK SURFACE, A MARKING PUNCH SLIDABLY FITTING THE SUPPORT BORE WHEN THE OPTICAL UNIT IS REMOVED AND HAVING A MARKING POINT AT ITS LOWER END IN THE SAME SPACE RELATIONSHIP WITH RESPECT TO THE SUPPORT BORE AS HAS THE RETICLE; SAID PUNCH HAVING A STRIKING PORTION WHICH WHEN STRUCK WILL CAUSE THE MARKING POINT TO BE DRIVEN INTO THE SURFACE OF THE WORK PIECE.