GB559022A - Improvements in or relating to measuring machines - Google Patents

Abstract

559,022. Linear measuring apparatus. PLAYER, D. S., LUND, J., and OPTICAL MEASURING TOOLS, Ltd. July 28, 1942, No. 10571. [Class 106 (ii)] An apparatus for linear measurements over a wide range comprises in combination a bed with a guide way thereon, a movable anvil head or tail-stock, a fixed head, a setting bar upon the bed carrying gauge marks, an optical magnifying device and fine adjustment device associated with the movable head, and a measuring device associated with one of the heads for accurately indicating the subdivisions between the gauge marks. In the form shown the bed 11, Figs. 1 and 2, has guide ways 14 supporting a fixed head 15 and movable head 16. A recess in the bed receives a setting bar 18 set in position by locating screws 21, 22. The surface of the bar 18 is formed with recesses 23, Fig. 6, to receive glass gauge blocks 24 located by blocks 25, a wedge 26 and springs 27, 28 and 29. On the upper surface of the glass block is a gauge mark 34 which after adjustment can be set accurately by pouring in a setting material such as a low melting point metallic alloy. The fixed head 15, as shown, comprises a distance block 36 and a measuring head 37 with a sliding anvil 38. The measuring head may be similar to that described in Specification 557,069. The movable head or tail-stock 16 carries a microscope ocular 46 through which an image 47 of a gauge mark 34 may be set with reference to engraved lines 48 on a screen. The setting is effected by a fine thread screw 49 mounted in a pedestal 50 which can be locked to the guides 14. The anvil 52 of the tail-stock is fixed relatively to the stock. Supporting rollers or other means may be provided between the anvils to support the workpiece. The setting bar may be made of material which has constant characteristics under changes of temperature.