Patent GB-886158-A (GB)
Title: Improvements relating to the design and construction of jigs
Inventor: WHARTON JOHN
IPC: B23B47/28
Filed: 1958-08-25
Abstract: 886,158. Jigs. WHARTON & WILCOCKS Ltd. July 27, 1959 [Aug. 25, 1958], No. 27219/58. Class 83 (3). A jig built up from standard elements as described in Specification 587,448 is adapted for drilling by the provision of an adjustable arm carrying 2 drill-bush. A base 1, Fig. 1, has an element 2 secured thereto, which carries a guideblock 3 having lugs 3<SP>1</SP> which locate an arm 4 having a drill bush 5 therein. The arm has a slot 6 through which protrudes a bolt for securing the arm 4, block 3 and element 2, to the base 1. A screwed-rod 11 projects from the block 3, and passes through a plate 10 secured to the arm 4, and the arm is located in the desired position relative to the block 3, by nuts 13. In a modification, two sets of nuts are provided on the rod 11, and a slot in the plate 10 is located between either pair of nuts to provide two positions of the arm 4. In a further modification, Fig. 4, the rod 11 is replaced by two rods 20 extending from a plate attached to the block 3, on each of which are a number of discs 21 of known thickness, separated by spacers of known thickness and of smaller diameter than the discs. A plate 10<SP>1</SP> on the arm 4 has apertures 24 through which the discs can pass, and has pivotally secured thereto a number of levers 25, which can be inserted between the discs 21 to provide different settings for the arm 4. To gain access to the work which is below the arm 4, the arm may be removed or the block 3 may be hinged to a second block secured to the element 2 and locked when drilling, by a latch pivoted in block 3 and engaging a pin in the second block. An inverted channel member may be used which is located in the lugs 3<SP>1</SP> on the block 3, and fits tightly over the arm 4. Several such members having various internal channel dimensions may be used for arms of various widths. The guide-block 3 may be rotatable about a vertical axis, in which case a spigot having a key is located in a keyway in the element 2 and the block has a corresponding hole which engages the spigot, the block being clamped by a screw engaging the top of the block, and screwed into the spigot. When the arm is turned to allow insertion or removal of the work, the arm may be mounted in a rotatable block 3, Fig. 8, and located in the drilling position by a second block 50, which may or may not be rotatable. The arm abuts against a stop on the block and is secured by a spring- loaded screw 52 carried in an adapter 53 mounted on the arm, which passes through arm 4 into block 50. A latch 54 carried by adapter 53 engages a circular extension on the block 50 and is locked in position to hold the arm 4 against the stop by a screw 56. When the work is to be bridged, a doubleended arm 4<SP>1</SP>, Fig. 9, is supported by a rotatable block 3, and a locking-block 50. In another modification when drilling holes on a pitch circle in the work, a column 60, Figs. 11, 11A, is passed through a central hole in the work, an adapter ring X being provided where required, which fits the hole and the column, and the column is keyed to the base 1. A graduated plate 65 at the upper end of the column provides an angular setting of the block 35, which is screwed into the column by a screw 69, and locked in the required angular position by two locking washers 69<SP>1</SP>. The arm 4 is located in the block 3<SP>5</SP> and locked thereto by a clamp 67 keyed to the block by a key Y, adjustment of the arm is by a screwed rod 11<SP>1</SP> and nuts 13. The graduated plate 65 may be replaced by a plate having peripheral holes corresponding to the holes to be drilled, and a locating pin in the block 3<SP>5</SP> to engage the hole in the plate.