Improvements in or relating to measuring devices for determining the inside diameters of elongated hollow chambers

Abstract

Abstract 463,361. Optical inspection-apparatus. LEHMANN, H. June 5, 1936, No. 15738. Convention date, June 5, 1935. [Class 97 (i)] [Also in Group XIX] A mechanical diameter - measuring device and a microscope are fitted to the objective end of a telescope to form means for determining the inside diameters of elongated hollow chambers, particularly firearm bores. A microscope attachment 4 for the objective tube 3 has fitted to the end a guide piece 8 for blocks 9, 10 sliding relatively to one another in a plane at right angles to the axis of the tube and which carry calliper pins 11. The blocks are pressed apart by a spring 13 located in a hollow 12 in the blocks one of which is provided with a scale 15 and the other with an index mark 15<1>. A plurality of index marks may be provided so that two index lines are always in the field of vision. The scale is illuminated by a bulb 14<1>. In a second form instead of a scale and index the blocks are formed with racks engaging a pinion in which is a pointer which moves on a scale. In a third form two spring pressed pivoted calliper members are provided in the tube, the bent ends passing through slots to engage the base while a scale and index are provided on the inner ends of the calliper members which are illuminated by reflected light from a bulb in the end of the tube. The end of the instrument may be provided with guiding means having two positions by which the calliper members may be guided in the rifling grooves or on the lands between the grooves.

Inventors

No inventors recorded.

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