Installing the Carriage on the Base
Cut the support bracket (piece 8) to shape, and drill a 15/32″ through-hole. Fasten the bracket to the top of the base right behind the guides. Now make up two bearing blocks (pieces 9). Slip them between the support bracket and the fence braces. These blocks will capture the head of the carriage bolt (piece 10) that moves the carriage back and forth. Mark the centerpoint for this bolt hole by sticking your 15/32″ bit through the hole in the support bracket and pricking the back bearing block. This block receives a 5/16″ bolt hole and a counterbore for the bolt head. Drill those holes now. The long carriage bolt will spin inside the bearing blocks if you grind or file off the “flats” under its head. When that’s done, fasten the front bearing block to the fence braces, slip the bolt through the rear block and glue and screw the two blocks together. I smeared a dollop of paste wax into the bolt head counterbore first, to help it twist easily.
Your last step to installing the carriage is to screw a threaded insert (piece 11) into the support bracket hole you drilled earlier. Slide the carrier onto the base, and engage the carriage bolt and insert. Wind the bolt far enough through so you can spin on a jamb nut and the adjustment knob (pieces 12 and 13). Test the action of the carriage by turning the knob in both directions. If things work smoothly, remove the carriage, sand the parts and apply finish.