| 摘要 |
PURPOSE: To compensate a dimensional difference due to tolerance so as to reduce vibration of a driving shaft by forming at least one of supporting ribs with elasticity in the radial direction in a portable freely cutting device. CONSTITUTION: At least three supporting ribs 8, 9 are necessary for positioning a shaft supporting sleeve 7 in the center of a protective tube 1, and at least one supporting rib 9 in these supporting ribs 8, 9 is provided with elasticity in formation. In the rib 9, a first part 9a connected in the radial direction precisely to the shaft supporting sleeve 7 is connected to a second part 9b which is positioned in the substantially tangent direction to the shaft supporting sleeve 7 and provided with a head part 20 touching the inside face of the protective tube 1. In this constitution, the supporting rib 9 with elasticity compensates a dimension difference due to tolerance when the shaft supporting sleeve 7 is assembled inside the protective tube 1, so that deformation of its shape is hardly caused. In addition, the supporting rib 9 hardly transmits shaking or vibration to the protective tube 1 because of its elasticity, and transmission of shaking or vibration to the outside can be prevented.
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