How to Use a Drill Press for a Hollow Mortising Chisel

Turn off the drill press and loosen the chuck with the chuck key to remove any bit in the chuck.

Slide the mortising attachment over the chuck and onto the base of the drill press. Tighten the mortising attachment's collar into place with an Allen wrench.

Insert the square mortise chisel into the attachment, and tighten the chisel collar to hold the chisel in place. Then, slip the bit upwards through the hollow chisel and into the drill press chuck. Tighten the chuck with the chuck key to hold the bit in place. The bit should be positioned so that the cutting faces are about 1/16-inch lower than the edges of the chisel.

Place the board to be mortised onto the drill press table, and adjust the table's height so that the base of the chisel is 2 inches above the wood.

Adjust the mortiser's hold-down clamp so that it is about 1/8-inch above the wood to be mortised. Tighten the clamp in place. The wood should be able to slide left and right for adjustments, but the wood should not be able to be lifted upwards.

Adjust the belts on the pulleys above the drill press head unit so the drill will operate at a speed between 1,000 and 1,500 rpm. Consult the chart mounted in the lid of the drill press for the exact placement of the two belts to achieve this speed.

Slide the wood out temporarily from under the hold-down. Pull down on the drill press lever to lower the bit and check the depth of cut. Adjust the drill stop until the bottom of the bit will be stopped at the desired depth of cut.

Place the wood back under the hold down. Position the wood so that one edge of the area to be mortised is directly beneath the bit.

Turn on the drill press. Pull down on the drill lever to lower the bit into the wood. Do not force the bit into the wood, but allow the bit to do the work. When you reach the bottom of the cut, lift the arm to pull the bit out of the wood. Slide the wood to the next position, and repeat until the entire mortise is drilled.