SIDE CUTTING DEVICE

1495914 Side cutters ARMADILLO HOLDINGS Ltd 10 March 1976 [16 April 1975] 09540/76 Heading E1F A side cutting tool for use in straightening a pilot borehole drilled from a lower to an upper chamber includes a pipe 16 for connection to the top of the drill string in place of the pilot bit once the. latter has broken through into the upper chamber. Extending from side of the pipe is a box-section cutter 18 composed of sharp-edged plates 20, 23 of which the plates 20 have tangs 29 and converging slotted trailing ends 32, 33, while plate 23 has its ends 23, 24 curved inwards towards the pipe. In use, the tool is oriented with the cutter disposed at the side of the pilot bore which needs to be cut away to straighten the bore, and the tool is then reciprocated to enlarge the bore. On each down stroke, the cutter cuts out a rectangular plug of material from the side of the bore, and on the succeeding upstroke the cutter carries the plug out of the bore.