GB646248A - Improvements in or relating to bore comparators - Google Patents

Abstract

646,248. Gauging-apparatus. MAURER, J. July 2, 1948, Nos. 17919 and 17920. Convention dates, July 2, 1947 and June 21, 1948. [Class 106 (ii)] A bore comparator comprises a feeler whose movements are transmitted to a dial gauge through a spindle, the feeler and spindle each being integral with a rack engaging a common pinion. An extension 3 is screwed into the casing of a dial gauge 1 and is formed with a hole 5 in which freely slides a rod 6 pressed by a spring 8 against the plunger 9 of the dial gauge, a stud 18 preventing rotation of the rod 6. A feeler 10 slides in a guide at rightangles to the rod 6 and both feeler 10 and rod 6 are formed with racks meshing with a common pinion 17, the dial gauge spring overcoming the spring 8 to extend fully the feeler 10. Interchangeable parts 20 formed with stops 23 of different sizes are provided and further centring means comprise stops 31 on legs 30 symmetrically placed with respect to the feeler and formed in a plate 24 hinged at 25 and urged counter-clockwise by a spring 26. In a second embodiment, Figs. 5, 6 the stop 23 is supported by a part 34 screwed into a sleeve 35 slit at 36 and secured to the extension 3 by screws, the part 34 being adjusted by a knurled knob 39 and locked by a screw 38 drawing the halves of the sleeve together. The comparator is centred by a plate 41 having two cylindrical guides 43 sliding in holes symmetrically located each side of a cylindrical part 42 with springs 44 urging the plate 41 outward and pins 45 to limit this movement, three-point contact being made by the stop 23 and in curved rims of the plate 41. Fig. 7 shows a comparator similar to the first embodiment but having the interchangeable member 20 in the form of a gauge block held by a screw 22. A flange 50 with U-shaped part 51 embracing the extension 3 can be clamped in any position by means of a knurled head 53 controlling an eccentric 52. To set the comparator to measure a particular dimension set up on a micrometer, a button 32 is pressed to free the rod 6 temporarily from the plunger 9, the flange 50 is clamped near the block 20 so as to hold the centring means 31 retracted and the comparator is introduced between the anvils of the micrometer until a face 55 of the flange 50 abuts the anvils and is oscillated slightly until the dial reads the highest value corresponding to the required dimension. The comparator is then introduced into the bores to be gauged either with the flange clamped to set the depth the measure is to be taken or the bores are gauged without using the flange, the comparator being slightly oscillated to ensure a reading on a diameter.