Patent GB-316131-A (GB)
Title: Improvements in or relating to measuring devices for drilling and like machines
IPC: B23Q5/32
Filed: 1929-06-11
Abstract: 316,131. Soc. Genevoise d'Instruments de Physique. July 23, 1928, [Convention date]. Drilling.-In a device for enabling alined holes to be drilled or milled &c. on opposite sides of a work-piece, the work a is secured to a rotary table c which may be moved transversely to the axis B<1>-B<2> of the tool f by means of a screw p, circular scales r<1>, r<2> reading in opposite directions being provided on the screw and linear scales s reading in opposite directions being provided on the machine bed m so that after drilling one hole g the work may be rotated about the axis o of the table through 180‹ and the scales adjusted to produce an alined hole in the opposite surface b<2> of the work with the same scale readings as were used to determine the position of the hole g. The linear scales s, which co-operate with a pointer t on the slide n, are provided on opposite sides of a bar which is rotatable about its axis to expose either scale to view, the arrangement being such that rotation of the bar moves a shield v over one or other of the scales r<1>, r<2> so as to expose the corresponding linear and circular scales simultaneously. In operation, the position of a hole g is located relatively to the tool f by means of the screw p, linear scale s and rotary scale r<1>, the ordinate x<2> being measured from some such point as the edge of the work. After the hole has been drilled, the table c is moved so that the axis of the tool passes through the centre o, this position being indicated by a mark w on a disc y secured to the screw, and the scale r<2> is then rotated on the screw and frictionally locked in a position in which it gives the same reading as the scale r<1>. The work is then rotated through 180‹ and the ordinate x<2> again set off by means of the scale r<2> and its corresponding linear scale s, a hole then being drilled at g', concentric with the hole g. The scales s determine the whole units of measurement and the scales r', r<2> the fractions, such as hundredths of millimeters. The scales s may be provided on separate rods, each with its own pointer, and optical or mechanical magnifying systems may be provided. The neutral position of the table c may be indicated by a pointer on the table and a mark on the bed, instead of by the disc y, with or without magnifying means. The table may receive rotary motion only and the transverse motions be performed by the toolhead. In a modified construction the rotary scales r<1>, r<2>, Fig. 5, are mounted on the screw p with a slight amount of friction and their inner edges are toothed to gear with a pinion on a radial axle carried by the screw, so that rotary adjustment of one scale will cause an equal and opposite rotation of the other, the pointers q<1>, q<2> always indicating the same numerical reading on each scale. Two pointers t<1>, t<2> are provided for the scales s, each being slidable relatively to the carriage n by means of a pinion u<1> on the carriage and racks on the pointers. The rod having the scales s thereon carries a bevel pinion engaging a pinion z<2> on the shield v<1> for the rotary scales, the whole being actuated by a handle k. In operation, the scales and pointers are set to give a whole number reading when any point on the work, such as one corner, is on the line B<1>-B<2> of the tool spindle. On reversing the work and moving the table until the same numbers are indicated, the alined point on the opposite side of the work will then be on the line B<1>-B<2>.