| 摘要 |
PROBLEM TO BE SOLVED: To provide a boring device for making a hole on an inner wall surface of a building or the like, capable of executing the boring with comparatively small load by efficiently transmitting the torque of a driving source to a cutting edge, preventing the cutting edge from being flared during the cutting, and easily replacing the cutting edge even though a edge tip of the cutting edge is worn out in accompany with the use, and including a means for improving the cutting quality of the edge tip. SOLUTION: The endless cutting edge and a driving mechanism for rotating the cutting edge are assembled in a casing, the driving mechanism can be advanced or retracted in the direction along the rotating spindle, a biaxial sprocket pulley is mounted to the driving mechanism, a timing belt engaged with a circumferential surface of the pulley is formed on a basic part of the endless cutting edge, and one of the two pulleys can be separated from or approached to the other pulley.
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