| 摘要 |
A device to aid the user to drill a hole in the exact transverse center of an elongated object, such as the edge of a board to be joined by dowels. It has a single pivoted cross which expands and contracts in response to movement of a pair of spaced parallel channels that contain the cross. Channel movement is controlled by a clamp screw acting in conjunction with spring means urging the channels apart. The ends of the arms of the cross carry locator pins equidistantly spaced from the pivot axis, so that as the locator pins snugly retain both sides of the object to be drilled, the pivot axis is automatically centered.
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