Center locator for alignment of work to machine spindle

Claim 1

A center locator for use with a drill press or like tool having a rotatable spindle and a chuck or other tool holder attached to an end of the spindle: (a) a case or housing of electrically conductive material having a shank for coaxial connection to said chuck or tool holder; (b) said case having a bore aligned with the shank axis; (c) a barrel part guidingly mounted in said case bore for angular movement about said shank and bore axis, as well as for axial movement therein, said barrel part being made of electrically conductive material; (d) said barrel part having an annular groove; (e) a retractable hollow screw mounted on the case and cooperable with said annular groove for limiting axial movement of said barrel part; (f) An incandescent lamp having a bulb part extending into the inner end of the barrel and having a flange of electrically conductive material in engagement with the said end of the barrel part, said lamp having a contact button located beyond the inner end of the barrel; (g) means cooperable with the lamp bulb for holding the lamp to the barrel, comprising three relatively soft plastic screws adjustable to center the lamp at the axis; (h) a magnifying lens accommodated in the opposite outer end of the barrel and fitted against a shoulder in the barrel; (i) a resilient O-ring frictionally fitted in the barrel releasably to hold the lens in place; (j) said lens having pattern means imprinted or otherwise formed thereon; (k) spring contact means carried by the case for engagement with said lamp contact button upon axial movement of said barrel; (l) a coiled contact spring in said screw and in continuous wiping contact with said barrel part; and (m) batteries carried by the case and imposing an electrical potential between the case and said spring contact means.