Hand-held drill bit tester

Abstract

A compact tester for examining the sharpened end of a twist drill bit for geometrical symmetry and angular relations. The tester includes an optical system for examining the sharpened end; a holder adapted to hold bits of various diameters so that their cylindrical axes coincide with the optical axis; and a reticle having markings which appears to the eye of the user superimposed on the image of the bit end. The holder is a short tube with plural, nesting spiral springs extending from the inside surface of the tube inward. Each spring is a rectangular sheet of spring steel wrapped so as to present a spiral shape when viewed end on. The springs automatically hold bits centered in the bore of the tube, which is aligned with the optical axis. The optical system may be a simple magnifier, or something more sophisticated. The reticle may be a separate flat glass with markings, or, the markings may be put directly onto the magnifier. The markings include concentric lines and radial lines, and means for measuring angular relations. The reticle may be rotated to align it with the bit.

Dependencies are inferred from the claim text.