GB686411A - Improvements in or relating to linear-dimension gauges - Google Patents

Abstract

686,411. Linear-dimension gauges. EBAUCHES SOC. ANON. May 4,1950 [May 4, 1949], No. 11097/50. Class 106 (ii). A linear-dimension gauge comprises a graticule mounted in a feeler and a second graticule secured in the body of the gauge, the graticules being so marked and arranged that when the feeler is displaced by a work-piece the marks indicate whether the work-piece is within predetermined tolerance limits. In one embodiment, the invention is applied to the internal gauge described in Specification 646,992. The movable feeler 5, Fig. 2, is held in known manner in the innermost position to which it is pushed during a gauging operation against a spring, by a wedge brake. A transparent scale 8 carried by the feeler moves adjacent to a fixed transparent graticule 11 bearing a vernier scale 12, Fig. 3. After the gauging operation, the scale may be read through a magnifying lens 13 arranged in a transverse hole in the gauging head. The graticule 11 also bears a line 16a and lines 17-19 which co-operate with elongated graduations of the scale. The lines 17-19 are marked according to the tolerances allowed for certain standard fits. If for a particular fit the corresponding line, say 17, is to the left of the adjacent elongated scale marking and the line 16a is to the right of the elongated scale marking adjacent thereto, then the dimension gauged is within the limits of tolerance. Additional lines similar to the lines 17-19 may be provided for other standard fits and some of these may be arranged in a lower row, the elongated scale markings being correspondingly lengthened. For external measurements, the normally fixed gauging anvil of a micrometer may be formed in a similar fashion to the feeler 5 shown. In this case, the spindle of the micrometer is set to the nominal size of the work-piece and the fixed graticule 11, Fig. 5, bears for each range of dimensions, e.g. for the range 0-3 mm., a series of short, parallel lines 27 arranged in pairs, each pair corresponding to the tolerance range for a given standard fit. The moving graticule carries a single line 28 for each range. If this line falls between the appropriate lines 27, the dimension gauged is within the chosen tolerance limits. A feeler 5 associated with graticules, similar to the graticules 8, 11 shown in Fig. 5, but for one range only, may form one calliper of a non- adjustable gauge constructed for a given nominal size of work-piece.