Abstract: A pair of anvil pins are mounted at their lower ends on a pair of spaced carriers, which reciprocate beneath a work supporting surface in horizontally spaced, colinear paths. The pins project upwardly through an elongate slot in the work surface and into a bore in an annular workpiece positioned on the surface. One carrier is urged by a spring in one direction to cause its anvil pin to urge the outer periphery of the workpiece into a V-shaped recess in a locator plate that is adjustably secured on the work surface, thereby to center the workpiece over the slot. An indicator mounted on the other carrier has a resilient probe extending between the carriers to urge them apart, and thereby to urge their pins against diametrally opposite sides of the bore, whereby a readout on the gage will indicate the extent to which the I.D. of the bore differs from a predetermined value. One pin is adjustable on its carrier to accomodate the gage for measuring particularly large or small bores.

Abstract: An indicator is made to fit within American Gauge Design dimension requirements to be compatible with existing accessories for indicators and still have a spindle with a travel of about 1/2 inch cooperating with an electro-optical, digital electronic measurement and readout system. A coupling is secured to the inner end of the spindle and supports a ruled glass scale for movement with the spindle in an axially offset position to move relative to a reader assembly that is mounted in the housing. A connecting arm is secured to the coupling for movement in a region spaced from the scale, a lifter rod is arranged opposite the spindle, and a lifter arm is connected between the lifter rod and the connecting arm so that the lifter rod moves about one-half the distance of the spindle. The connecting arm also prevents rotation of the spindle to maintain the orientation of the scale relative to the reader assembly.

Abstract: A digital electronic micrometer eliminates backlash and other error between a movable probe and a digital readout and arranges all the working components within a handle thermally insulated from the probe and the yoke. An optical scale is secured to the probe to move directly with the probe past an electro-optical reader arranged within the tool handle, and a manually operable retractor moves the probe away from the anvil against the bias of a spring. Electronic circuitry and digital display can also be arranged in the tool handle for indicating positions of the probe relative to the frame, and the circuitry includes manually actuatable hold circuitry for maintaining the display at an indication of a previous position of the probe after movement of the probe. This allows the tool to be moved to an orientation for observing a measurement previously taken when the tool was in a position obscuring the reading.