Drilling Front and Back
Cut front and back faces to 2-3/4-in. x 2-3/4-in. Secure the pieces with a clamp and then drill the speaker holes in the center of the front and back faces. Use a 1-7/8-in.-dia. forstner bit, spade bit, or hole saw to bore the holes.
Assembling the Box
Sand all of the parts smooth, then assemble the box. Place the sides, top and bottom pieces in order, face down on a piece of tape. Apply glue to the miters. Then place the front and back pieces in the dadoes in the first piece and gently roll the box sides together (inset). Make sure the front and back pieces fit into the dado in each piece. Use the tape to secure the box sides and then clamp the assembly with band clamps (inset).
Cutting the Spline Slots
After the box assembly glue up had dried, cut spline slots using a router table and spline cutting jig. The Rockler Router Table Spline Jig is secured in the router table miter slot. It features a sliding cradle that safely secures work piece and aligns it with the bit to cut consistent spline or key slots.