This device helps prevent the underside of veneered plywood from splintering by scoring the veneer just ahead of the blade. To make it, cut a snug-fitting insert blank from aluminum or plywood. Carefully raise the blade through it and enlarge the slot for clearance. With a straightedge against the teeth on each side of the blade, mark the outer edges of the blade’s kerf on the front section of the insert. Cut along these lines with a thin saw to create two slots just ahead of the blade.

The scoring assembly uses two circular blades from the relatively new circular scissors made by Olfa. Spare blade packs for the scissors should be available at sewing and fabric stores. Make up a pillow-block assembly with a bolt axle to attach the scoring blades to the underside of the insert. Use regular washers, as well as shim washers punched from an aluminum can, to space the blades on the axle. Bolt the scoring assembly under the insert, making sure it will clear the sawblade and housing when in place. Ideally, the scorers should make a shallow cut (1/32 in. to 1/16 in.) in the plywood very slightly wider and in line with the kerf of the blade.

Sandor Nagyszalanczy, Santa Cruz, Calif.

Fine Woodworking Magazine, October 1986 No. 60

Fine Woodworking Recommended Products

Veritas Standard Wheel Marking Gauge

A wheel-type gauge is the easiest to use, and this wonderful Veritas model is a steal at $38.

Buy at Lee Valley

Double Sided Tape

A thin woven core makes XFasten tape strong yet not too thick (0.008 in.), and helps it hold powerfully without being difficult to peel off.

Buy at Amazon

Rockler Deluxe Panel Clamp

These clamps can handle glue-ups between 10 in. and 36 in. wide, and boards up to 3 in. thick. Sliding feet attach to the lower bars with magnets, letting you position them quickly for stability on any surface. The spring-loaded jaws adjust easily, dropping into notches along the bars. And the powerful clamp handles clear the benchtop.

Buy at Amazon