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.

Abstract: A magnifying device for use with a hand-held video display apparatus or the like having a generally rectangular housing and a video display visually observable from externally of the housing. The magnifying device includes a frame adapted for releasable mounting on the video display housing, and has a magnifying lens adapted to overlie the video display and effect magnification of the video display during operation when the magnifying device is mounted on the video display apparatus.