GB513263A - - Google Patents

Abstract

513,263. Gauging screw-threads. HOOPER, A. E. March 31, 1938, No. 9842. [Class 106 (ii)] [Also in Group XX] A bar or strip formed at one edge with teeth having the correct form and pitch is supported with this edge in mating contact with the screw,' hob &c. to be gauged and means are provided for producing a magnified image of the contacting edges. The shank portion of a T-shaped master form 1, Fig. 2, is received in a groove 2 in the rear face of a holder clip 3 adapted to be supported on a transverse beam 4 of a known form of optical projection apparatus. The teeth on the master form are of the correct shape and pitch and are preferably bevelled to a knife edge 1a. The beam 4 is of dovetail section and the front face of the clip 3 is undercut at 3a to take over the upper edge. The form 1 is adjustable in the groove 2 sliding over a screwed stud 5 by, means of slot 1c and clamped by a nut 6. The clip 3 is adjustable along the beam 4 which is slidably engaged at the ends in bracket 7 in turn adjustable along a beam 8 carried, in brackets 9 adjustable vertically on pillars 10 secured to a carriage 11. Each bracket 7 carries a centre between which the work to be tested, a screw gauge 12, is supported. A light source directs a parallel beam along the axis 15 and through the lens system 14 and throws a magnified shadow of the screw and form on to a screen, Variations in the thin ribbon of light between form and gauge are due to errors in the gauge. In a modification two exactly mating master forms are each mounted at the extremity of a U-shaped metal casting. In a fourth form, two pillars are formed on a base and carry centres supporting the screw to be gauged. A shaft intermediate the centres and the base supports a bracket carrying at the upper ends a slidable master form the upper end of which engages the plunger of the dial gauge. The central part of the bracket is formed as a ring to allow projection of the mating contact surfaces.