Homemade Disk Sander

Cut one of the pieces of plywood into a 10-inch-diameter circle with a band saw or jigsaw.

Cut the 2-inch by 4-inch board into two lengths of 10 inches and two lengths of 7 inches, using a circular saw. Stand the four boards on edge, and align the 7-inch sections between the 10-inch sections, forming a 10-inch square. Place the remaining plywood square over the 2-inch by 4-inch board square, and attach the plywood to the four boards with four wood screws into each 2-inch by 4-inch board. This will form a table for supporting the workpiece when sanding.

Drill a 1/4-inch-diameter hole through the pulley, 1 inch in from the edge. Drill three more similar holes at 90-degree intervals around the pulley.

Align the plywood over the pulley, and mark the hole locations on the plywood with a pencil. Drill 1/4-inch-diameter holes through the plywood at each of these locations. Countersink the holes by drilling with a larger bit only deeply enough to allow the bolt heads to be flush with the face of the plywood.

Slip the pulley over the threaded motor drive shaft, and secure the pulley to the drive shaft by tightening the nut with a socket set.

Insert the bolts through the plywood with the heads flush with the face of the plywood. Insert the four bolts in the holes in the pulley, and secure the two with washers and lock nuts on the bolts. Tighten the nuts with a socket set.

Place a 10-inch sanding disk over the face of the plywood. Position the small work table you created in Step 2 in front of the disk. Turn on the motor, and place the piece to be sanded on the table for support while holding the piece against the spinning sanding disk.