Patent GB-743496-A (GB)
Title: Scale dividing and linear interpolating machine
Inventor: RZYMOWSKI EUGENUSZ KLEMENS
IPC: B44B3/00
Filed: 1953-04-11
Abstract: 743,496. Dividing-engines. NATIONAL RESEARCH DEVELOPMENT CORPORATION. July 9, 1954 [April 11, 1953], No. 9919/53. Class 97 (3). A scale dividing and linear interpolating machine comprises a surface cam of axially uniformly varying Archimedian spiral crosssection, of which the spiral surface starts from an inner datum parallel to the axis, angularly movable through a dividing mechanism over a number of equiangular spaced positions beginning with the datum position, the cam being movable axially relative to a transversely disposed cam follower which moves the scale beneath a scale marking tool controllably guided over the scale, so that relative axial positioning of the cam and follower, when the cam is in its extreme angular position measured from the datum, serves to divide the scale beneath the marking tool into a number of definable main divisions, while equiangular movements of the cam between its extreme angular positions serves to interpolate the scale linearly between the main divisions. As shown, the cam 1 has an Archimedian spiral cross-section which varies linearly along its axis and starts from an inner straight line datum parallel to the axis. The cam is mounted between centres 2, 3 to be rotatable about its axis by a handle 4 having a spring detent engageable in equally-spaced holes 5 in a dividing head 6. The cam and its mounting is slidable in guides on a bed 7 by a handle 8 and a screw drive. A frame 9 mounted at the side of bed 7 carries a slidable cam follower 10 spring-urged into contact with cam 1, and a pair of hinged V-clamps 12, 13 holding a cylindrical part 17 of a microwave wavemeter 18 in which a cylindrical scale-bearing part 16 is screwed. A toothed sector 19 is releasably attached to scale part 16 and meshes with rack teeth formed in cam follower 10. To mark the scale, the wavemeter is tuned to a convenient frequency by adjusting scale part 16. The part 16 is held in its adjusted position by a friction pad 20 until the toothed sector 19 is clamped to part 16 with the follower 10 in contact with the cam at its inner datum. A tool-holder 14 is depressed and a main division is made on the part 16 by means of a tool 15. The cam is turned clockwise to its other extreme position, and then adjusted longitudinally so that the wavemeter is tuned, by means of cam follower 10, sector 19 and scale part 16, to a new frequency at a convenient interval from the first, and a second main mark is made. The handle 4 is then turned to a number of equally-spaced positions wherein its detent engages the holes 5 and a mark is made in each position, the tool-holder being adjusted so that the sub-division marks are smaller than the main marks. The tool is then re-aligned with the last main mark, scale part 16 is clamped by pad 20, and sector 19 is released. The cam 1 is rotated until its inner datum is again in contact with the follower 10. On re-clamping sector 19, further main marks can be made successively and subdivided, so that a helical scale is formed. The subdivisions are evenly spaced, though the main divisions are not, and application of the apparatus is restricted to cases where the error so produced is not important.