| 摘要 |
The tool is for boring tapered holes, widening out downwards in concrete for holding-down bolts. A threaded spindle carries a hard metal blade at its tip and employs a collar with downturned spikes extending from it, to hold it in position on the surface of the concrete. A smaller collar is mounted by a sleeve on the spindle, so that by rocking the tool, a tapered hole is formed as the tool is rotated. The larger collar has a curved depression forming a seating for the concave face of the smaller collar to permit the rocking action. |
