My boring jig, which uses a 1/2-in. portable drill, is similar to a conventional horizontal-boring machine except that the table moves rather than the drill. The jig consists of a base, a hinged drill platform and a sliding table.

Make the base and sliding table from 3/4-in. hardwood plywood. The drill platform should be extra stiff, so laminate two pieces of 1/2-in. plywood to give a 1-in, thick platform. Spindle elevation is adjusted by raising or lowering the hinged drill platform. Install a piano hinge on one edge and two or three bolts with wing nuts for adjustment on the other edge. If adjustment is needed over a wide range (say, 3 in.), some sort of pivoting arrangement would be required for the adjustment bolts.

Most 1/2-in. drills have a threaded handle socket on the top or side that will accept standard 3/4-in. threaded pipe. Secure the drill to the platform with a short piece of threaded pipe and a standard floor flange.

Elevating the platform swings the drill through a short arc, so the fence on the sliding table must be mounted through slotted bolt holes to allow for movement. Hardwood rails on the bottom of the table mated with hardwood guide blocks on the base provide the tracking action for the sliding table.

Vanessa Skedzielewski, Sierra Madre, Calif.

Fine Woodworking Magazine, April 1980 No. 21

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