GB792427A - Improvements in or relating to drilling and boring jigs - Google Patents

Abstract

792,427. Drill-jigs. FREEMAN, H., and GARDNER, R. June 21, 1956 [June 21, 1955], No. 17948/55. Class 83 (3). A drill-jig comprises a longitudinally-slotted bar 10 with a hole 12 at one end, having its centre in line with the centre-line of the slot 11, and drill-bushes 14 to fit the slot and hole and having shoulders 16 to engage the bar and screw-threads for nuts 18 to clamp the bushes to the bar. For jigging a circumferential row of holes a number of bars may be provided, the bars being connected by a bush 14 through their holes 12, and secured to a circular, or partcircular, member 21 by bolts 23 passing through the slots 11 and one or more slots 22 in the member 21. Enlargements or sleeves on the bolts 23 locate the member 21 above the planes of the bars, and the lengths of the bushes differ in order that their ends may be in a common plane. Both ends of the bars may have holes for the bushes. In use, a plug in a hole in the work locates the bush engaged in the holes 12. A hole is then drilled, using one of the other bushes, and a further plug engaged in this hole and the bush. By this means the jig is located while holes are drilled beneath the two remaining bushes, subsequent holes in the circumferential series being drilled in pairs as the jig is moved around and located by the central hole and the last hole of the series.