Patent GB-557578-A (GB)
Title: Improvements in or relating to comparators or like measuring instruments
IPC: G01B5/24
Filed: 1942-02-23
Abstract: 557,578. Comparators. COOKE, TROUGHTON & SIMMS, Ltd., and TAYLOR, E. W. Feb. 23, 1942, No. 2373. [Class 106 (ii)] Relates to instruments with an adjustable work table and in which one anvil is attached to a tailstock having a fine screw adjustment and the other to indicating mechanism and slip gauges are used between the anvils to build up a dimension, the indicating mechanism being brought to zero by a tailstock adjustment, and consists in introducing an interruption in the continuity of the mechanical parts so that slip gauges may be inserted or removed at some point between the anvil contacting the work and the indicating or tailstock to increase the normal range of the instrument. A taper plug gauge 1, Figs. 1, 3, is mounted between centres in a cradle 2 clamped to an upper table 3 by a finger screw 4. The cradle 2 may be moved in the plane of the section, Fig. 3, by rotating the screw 6 against the action of a spring claw 7. The upper table 3 moves freely on balls 8 on the lower table 9. The latter is supported by two rollers 10 which engage grooves in the part 9 and in the cross piece 11. Springs 12 hold the parts 9, 10, 11 together. The tables 3 and 9 may be rocked about the common axis of the rollers 10 through a pin and slot mechanism 14, 15 from the knurled head 16. The cross piece 11 is secured to the top of a column 19 which may be moved up and down from a handwheel 20 by pinion and rack mechanism (not shown). A pointer 23 and scale 21 shows the positions of the table 3. The body 22 receives a horizontal bar 24 on which slides tailstock and indicator brackets 25 and 26. The tailstock 27 carries an anvil 28 adjustable axially by a fine screw. The bracket 26 is bored to receive an indicator 29 having an anvil 30 moved to the left over a limited range by a light spring. The anvil may be moved to the right by a lever 33. Attached to the indicator is a bracket 34 bored to receive a pushrod 35 terminating in anvils 36, 37 and urged to the left by a light spring 35A. Attached to the cross piece 11 is a block 38 and loosely secured to this is a second block 39 in such a manner that it can pivot about a ball 40 and square itself to the surface of the bracket 41 attached to the body 22. Slip gauges may be readily inserted between the blocks 39, 41. In use, the tapered gauge 1 is mounted between the centre in cradle 2 and the latter clamped to the table 3. The cradle and work are lowered by rotating wheel 20 until blocks 39, 41 make contact with each other or with a slip gauge between them. Next anvil 28 is brought into contact with the gauge, moving bracket 25 as necessary, and the cradle 2 and table 3 moved to the right and bracket 25 clamped. A slip gauge is inserted between anvils 30 and 37 and the bracket 25, indicator 29, and bracket 34 advanced until the work 1 is contacted. The bracket 26 is clamped. The cradle 2 and gauge 1 are moved in the plane of Fig. 3 by means of a knurled head 6 until index 31 gives a maximum reading. The anvils 28, 36 are now making contact in the axial plane of plug 1. The work and cradle are rocked about the rollers 10 by using head 16 until the indicator gives a minimum reading. The anvils 28, 36 then contact at the ends of a diameter of the plug. The tailstock is adjusted so that indicator reads zero. Now the gauge is turned between centres to check circularity. The table is now raised a known amount by inserting an appropriate slip gauge. Further slip gauges are inserted between anvils 30 and 37. Fig. 4 shows a construction for measuring taper holes. The bracket 34 and cradle 2 are removed and brackets 44, 45 are clamped to the tailstock and indicating mechanism. Steel ball ways 46, 47 on which move carriages 48, 49 are provided on the brackets. Attached to the carriages are clutches 50, 51 carrying contact tips 52, 53, 54, 55. The inner pair contact the surface of the hole and slip gauges are inserted between the top 55 and the indicating anvil.