| 主权项 |
1. A guide for a hole saw for making a new larger hole in a planar work piece with an existing hole having a circular cross section, a diameter and an axial length, the guide comprising:
a base sized to span the circular cross section of the existing hole, the base comprising a central aperture, at least three discrete first contact surfaces for abutting an interior cylindrical wall of the existing hole, and at least three discrete second contact surfaces for abutting an exterior surface of the work piece surrounding the existing hole; the at least three discrete second contact surfaces being substantially co-planar and being substantially perpendicular to the at least three discrete first contact surfaces; a shaft having a first end sized to be received in an arbor of the hole saw and a second end to be slidably and rotatably received through the central aperture of the base; and the base biased to be located at or near the second end of the shaft. |
