| 摘要 |
PURPOSE: A tool for extending the working length of a hand drill is provided to enable a worker to directly perform a drilling work in a ceiling by transferring the torque of a hand drill to a circle cutter through an electric shaft. CONSTITUTION: A tool(20) for extending the working length of a hand drill comprises an outer pipe(21), an electric shaft(22), bearings(23,23'), and a chuck(25). The electric shaft is inserted in the outer pipe. A shank unit(22b) is formed in one end of the electric shaft, and a coupling groove(22a) is formed in the other end. The shank unit is installed in the chuck of a hand drill. And the other chuck is connected to the coupling groove. The bearings are inserted into both ends of the outer pipe, and support the electric shaft. The chuck is installed in the end of the electric shaft through a connecting pin(26).
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