| 摘要 |
<p>A drilling tool has on its shaft 3 axially spaced notches 24 for selective engagement with a pin 23 attached to a collar 9 to vary its axial position on the tool. The drilling tool is provided at one end with a drill bit 4, the bit having lateral cutting edges. A bearing member 11 has an opening through which the shaft can be passed until the collar 9 engages with the bearing member, the arrangement being such that when the shaft is in a bore in masonry with the collar in engagement with the bearing member, the shaft can be swivelled in relation to the axis of the opening in the bearing member so that the end portion of the masonry bore can be widened out by the drill bit. The notches enable the unit to be used for varying masonry bore depths and the pin is biassed radially inwardly into one of the notches. <IMAGE></p> |
