Image Number 4 for United States Patent #5299609.
A positioning device is disclosed that positions and guides a nominally hand-held router or other machine tool for machining with respect to a workpiece that is used as a reference. A novel configuration is employed in which a main body holds a centrally located lead screw and attached micrometer dial. Two guide shafts are disposed flanking the lead screw. A transversely disposed yoke bar spans the lead screw and both guide shafts; these can each be locked in place by knurled thumscrews threaded into the yoke bar. A vernier adjustment knob rotating the lead screw drives the yoke bar and provides fine position adjustment that is both accurate and repeatable, and which can be locked by a knurled thumbscrew threaded into the yoke bar. The guide shafts accept the coarse adjustment by sliding through the yoke bar, where they can be locked in place by a pair of knurled thumbscrews threaded into the yoke bar to retain the coarse adjustment. The guide shafts return back upon and pass through the main body producing two novel features: firstly a novel folded or looped arrangement greatly simplifies and strengthens the mechanical configuration, and secondly the adjusting elements are entirely separated from the router or machine tool by the intervening main body.