| 摘要 |
An end of a rectangular scaled straight edge is pivotally connected to an end of a rectangular unscaled straight edge. The scaled straight edge has a longitudinal slot wherein a stem is retained by a compression lock. The stem passes through a hole in one end of a flat connecting bar that is disposed between a bearing of the compression lock and the scaled straight edge. The other end of the connecting bar is pivotally connected to the unscaled straight edge. When the lock is open, the stem is slidable within the slot, thereby providing an adjustable angle between the straight edges. When the lock is closed, the position of the stem is fixed within the slot, thereby sustaining a fixed angle between the straight edges.
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