Patent GB-702469-A (GB)
Title: A method of and instruments for ascertaining the distances between two unmarked points
IPC: G01B3/20
Filed: 1951-04-30
Abstract: 702,469. Linear-dimension gauges. SORENSEN, G. E. April 30, 1951, No. 10050/51. Class 106 (2) The invention comprises a linear-dimension gauge for ascertaining, without mental computation, the distance between two indiscernible points such as, for example, the distance between the centres of two holes that are spaced apart, or for ascertaining the distance from an indiscernible point, such as a hole centre, to a discernible mark. The gauge comprises, according to one example, a frame 13, Fig. 1, with a fixed terminal 14, a member 18 movable relatively to the frame 13 and carrying a second terminal 17, an elongated scale 27 slidable along the frame 13 and stop means 33 governing the movement of the slide 27 relatively to the movable member 18 and the frame 13. The member 18 can be secured where desired on the frame 13 by screw means 23 whilst the stop means 33 can l secured where desired on the elongated slide 27 by screw means 34. The slide 27 carries a scale that is visible through a window 21 in the member 18, the said scale giving readings which indicate only half the actual movement of the slide 27 relatively to the terminal 17. In the closed-together position of the parts, Fig. 7, indicium "“" inch is seen to register with index 22, this constant of a "“" inch being the distance between the medial points 14<SP>1</SP>, 17<SP>1</SP> of the two terminals 14 and 17 respectively as illustrated. For other cases, however, this constant will be one half the used width of the terminals 14 and 17 combined regardless of whether the widths of the jaws are alike. Method of use.-The gauge may be used to measure the distance between the centres C and c of two holes in a work piece W, Fig. 2. Let S = inch, D = 1 inch, d=¢ inch and X = 1¥ inches. Use of the instrument 12, Fig. 7, may be started with its sight box 18 loose on frame 13 and its stop 33 loose on slide 27 and slide handle 29 in abutting contact with frame bearing 28. Also stop 33 is in abutting contact with both frame bearing 28 and box member 18. At this time work meeting terminals 14 and 17 are closed together in mutually touching contact. To perform its measuring operation the instrument as shown in Figs. 7 to 11 is operated by changing the setting of its parts in what may be referred to as three stages, which stages may be performed in variable sequence with the same ultimate result. In one possible sequence of the said three stages of setting, the terminals 14 and 17, Fig. 8, may first be placed in register respectively with the nearest together points -N- and -n-, of the holes -H- and -h-, so that said terminals become separated to the extent of the rectilinear distance -S-. This separates box member 18 from stop 33 a like distance which, however, is fictitiously indicated as the idle dimensional magnitude ¥ inch in Fig. 8. This idle reading of ¥ inch may be mentally ignored, but is a function of the true distance 1 inch that jaws 14, 17 have actually been moved apart in the sense that it is half of said true distance plus the before explained constant “ inch. Box member 18 will now be fastened to frame 13 by tightening thumb screw 23. Scale slide 27 remains free to be shifted lengthwise toward the left in relation both to frame 13 and to member 18 which carries index 22. This completes the initial stage of setting. Next the idle existing reading of the above explained function of "S" will be modified mechanically without mental attention or need of observing the indicia on scale 39 as follows. First shift stop 33 from its position in Fig. 8 into abutting contact with box member 18, while the latter remains fast to frame 13 in its position shown in Fig. 9. Here the stop 33 will be fastened to the scale slide 27 by tightening thumb nut 34. Now by means of T-handle 29, scale slide 27, in unison with stop 33, will be pulled toward the left relatively both to frame 13 and to sight box 18 until stop 33 abuts again with frame bearing 28 as shown in Fig. 10. The extent of this mechanically determined movement of slide 27 is thus governed and limited by stop 33 so that it exactly duplicates the extent of previous separation of terminals 16 and 24 in Figs. 8, 9 and 10. Hence the initial relative movement between index 33 and scale slide 27 becomes doubled by mechanism operatively associating slide 27 with both frame 13 and box member and without resort to mental computation or need to observe the measurement indicating readings of the instrument up to this point. Index 22 is seen to register with indicium 1“ inches in Fig. 10, which is an intermediate reading that may be ignored. This completes the intermediate stage of setting. Now thumb screw 23 is loosened, and while stop 33 is kept in abutting contact with frame bearing 28, box member 18 is pulled farther to the right on frame 13 for further separating jaws 14, 17 until the work meeting terminals 15 and 25 sense the farthest apart discernible points -F- and -f-. This completes the final stage of setting. When this is done the true distance 1¥ inches between hole centres or unmarked loci -C- and -cis correctly indicated by index 22 against scale 39, this being the objective of the measuring operation. Modified constructions.-Similar gauges to the above, and operated in like manner, are also described but in which (a) the scale 39 is engraved on the scale slide 27 and the index 22 is engraved on the frame 13 and (b) the scale 39 is engraved on the frame 13 and the index 22 is carried by the stop 33.