| 摘要 |
There is provided a drill bit for cutting an undercut hole to a predetermined depth in a single continuous operation. The drill bit includes a body 1, a drill bit 3, a thrust transmitting member 5 arranged on the body, an undercut cutting member 13 housed in a guide groove 11, in the side face of the drill bit and a working force transmitting mechanism 23 in linkage with the thrust transmitting member and with the undercut cutting member to force the undercut cutting edge 15 outwardly of the drill bit against the action of a pull-up spring 18. <IMAGE> |
