| 摘要 |
A saw blade, saw and method for making circular openings in construction materials. The saw is adapted to be attached to a handle, motor and holder assembly so that an up and down stroking motion can be provided to the saw blade. The saw blade is concave in cross-section along substantially its whole length, and the degree of curvature of the blade is the same throughout the length of the blade that is concave in cross-section. The degree of curvature is that necessary to make a circular opening of the size desired. To make the opening, a circle of the size of the opening desired is drawn on the construction material, a hole is drilled in the construction material inside and abutting the circle of a size slightly larger than that necessary to receive the blade, the blade is inserted in the hole, and the cutting edge of the blade is moved around the circle.
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