Patent GB-1041381-A (GB)
Title: Apparatus for drilling spherical objects
IPC: B23B41/00
Filed: 1963-03-04
Abstract: 1,041,381. Drilling bowling-balls. D. B. SCOTT. March 4, 1963 [March 5, 1962], No. 8584/63. Headings B3B and B3C. Apparatus for drilling balls comprises a drill carriage 172 pivoted on a base about a first axis (tangential to the ball), means on the carriage for feeding the drill along a second axis, means for supporting the work for rotation about a third axis, and means for relatively displacing the drill and ball in a direction parallel to the first axis. A bowling ball has a thumbhole T, Fig. 5b (not shown), on a horizontal plane x-x, and finger-holes H 1 , H 2  spaced by the dimensions shown measured on the surface of the ball. The dimensions are " web " (w), and " span (d 1 , d 2 ) distances, the latter being different to account for finger-length differences. The thumb-hole is larger than the other holes so that if the projection of the end of the line BA falls at a point D so that P, the central reference point of the ball, bisects BD, the ball will be approximately in balance, the point P having been marked by the manufacturers to denote the side on which the holes are to be drilled. The axes of the holes are "pitched," that is, lie at an angle to a ball radius. Pitch is either forward as shown in Fig. 6b (not shown) or reverse.. A ball to be drilled is mounted in a support 111, 110 and secured by a screw-clamp rotated by a knob 113 with the reference point aligned with cross-hairs on a window 114, so that the ball occupies a position as shown in Fig. 5b with the axes x-x and y-y horizontal and vertical respectively. The drill is located with its axis coincident with the point P. The drill support is angularly adjustable about a shaft on an axis spaced by the radius of the ball from the centre of the ball support, the adjustment being indicated on a scale 124 to give the necessary pitch of a hole. Side pitch can be set in by rotating the drill support about pivots 126 by a hand wheel 154. The drill is rotated by a motor 162 and fed by rack-and-pinion gearing connected to a hand wheel 164. The drill is seated in a tapered chuck provided with an ejector. For setting the ball, a support shaft 102 is adjusted vertically by a hand wheel 103, upward or downward movement of the ball support (i.e. the web distance w) being indicated by scales beneath a window 106. The angular adjustment (i.e. for the span distances d 1 , d 2 ), is aided by a sight 209 to enable a pointer 108 to be moved by hand so that it is aligned with markings 763<SP>1</SP>, 764<SP>1</SP> (Fig. 7a, not shown) which are pre-set according to the drill diameter. The size of the drill is set into the machine by a knob 140 associated with a dial 702 beneath a window 141. Rotation of the knob also rotates a screw 707 to move the two web-distance scales 708, 709 beneath the window 106, the scales moving towards or from each other. Rotation of the knob 140 also rotates a gear 758 connected by a chain 759 to a gear 760 to rotate Bowden cables 765, 766 and adjust the span distance scales 763<SP>1</SP>, 764<SP>1</SP> behind windows 131, 132. The scales are also adjusted laterally to or from each other by a knob 142, Fig. 8 (not shown), having two scales to indicate thumb-span, the scales being corrected to allow for the fact that the distances d 1 , d 2  are not measured along the axis x-x. Rotation of the hand wheel 103 rotates an outer shaft 720, which is threaded to engage a bell-crank to raise and lower the ball-support shaft 102. Rotation of the wheel 103 also moves a nut 730 which, through linkage 732 moves a pointer 740 over the pre-set web distance scales 708, 709. To locate the finger holes equidistantly from the x-x plane the webdistance scales are graduated to half-scale so that the actual web distance between the holes is set on the scale for each hole on either side of a central marking 105, Fig. 1 (not shown). The thumb-hole is drilled centrally when the pointer 740 is beneath the marking 105. Within the shaft 720 is a shaft 722 rotated by a hand wheel 104 to rotate a screw 753, Fig. 7c (not shown), and tighten a clamp 756 about the shaft 102 to lock the work-support. In a modification, a handle 904, Fig. 9 (not shown), is moved upwardly to raise a shaft 902 carrying the work to adjust for web dimension and is rotated to adjust for span dimension. Drill size is set in by a dial 910 and a rack 907 to adjust a cam 905, which is tapered on all its surfaces. The cam 905 is moved between plates 926 to position the ball vertically for the thumb-hole, and is moved simultaneously against a stop 924 to locate the hole span-wise (dimension d 1 ), the stop being adjusted by a cam 935 set by a knob 937 which also sets a cam 949 through gearing 961, 962. To set the dimension d 2 , a knob 946 is rotated to adjust a cam 947 bearing on a stop 980 on an arm 944. For web location, the arms 944, 945 are positioned vertically by stops 971, 972. The cam 905 is thus held by the handle 904 against surfaces 977, 978 for one finger hole and 975, 976 for the other. The weight of the ball and its support is balanced by a weight 921, Fig. 10a (not shown), on a lever 924 supporting the shaft 902 through a ball 955. Springs 937, 939 act on the shaft 902 to tend to hold it in any position to which it is moved.