Precision adjustable router fence

An adjustable fence for attachment to a router to provide guidance along a workpiece, comprising:

• a main body configured with a horizontal baseplate portion having a vertically extending flange block, the flange block having (a) a first cylindrical bearing aperture running through a central region of the flange block and (b) a plurality of bearing apertures symmetrically flanking the first cylindrical aperture and disposed parallel thereto;
• an elongated threaded lead screw having at a first end thereof a cylindrical bearing portion in rotatable engagement with the first cylindrical bearing aperture;
• thrust means for constraining said lead screw axially relative to the flange block while allowing said lead screw to rotate;
• an elongated yoke bar mounted transversely on the main threaded portion of said lead screw and threadedly engaged thereto by a threaded aperture traversing a central region of the yoke bar, said yoke bar being configured with a plurality of bearing apertures corresponding to and aligned with the bearing apertures in the flange block of the said main body;
• a plurality of elongated guide shafts each traversing a corresponding one of the bearing apertures in the flange block and one of the bearing apertures in said yoke bar;
• a mounting pin bar secured transversely to said plurality of guide shafts at a first end thereof;
• a pair of mounting pins, for attachment to a router, secured to said mounting pin bar;
• vernier adjustment clamping means for manually clamping said lead screw against rotation in said yoke bar;
• coarse adjustment clamping means for manually clamping said yoke bar against travel along said guide shafts;
• and
• a vernier adjustment knob secured to a second end of said lead screw.

A positioning device, configured for locating and guiding an actual cutting tool for a nominally hand-held router or machine tool with respect to a workpiece for the purpose of machining said workpiece, said positioning device schematically constituting a chain of positioning elements comprising:

• a main body;
• a centrally located fine positioning adjustment;
• a transversely arranged connecting element splitting positioning effort effectively into two segments on either side of said fine positioning element, each of the segments providing a coordinated coarse positioning adjustment;
• and
• a pair of positioning elements that retain coarse adjustment and reverse the direction of the positioning effort forming a pair of loops that transmit the combined fine and coarse adjustments back through the main body and on to the machine tool.