Woodworker's Journal 1993-17-2, страница 40

the bottom edge of the base and to the straight edges of the swivel work support and stiffener. Start by ripping enough 7i6 in. thick by ⁷/« in. wide edging material to yield both the rub strips and the edging. Glue and clamp the ⁷/tt in. edging to the 7* in. thick plywood edges specified, then use a router (or laminate trimmer) equipped with a flush trimming bit to flush the edging with the plywood. Then glue and clamp the stiffener to the swivel work support, making certain that the edgings are perfectly aligned to provide a smooth work support surface.

Next, you'll need to lay out the holes for the two long machine screws (L) in the base and in the swivel work support/ stiffener subassembly. Bore the topmost V* in. diameter hole in the subassembly for the machine screw that holds the topmost of the two knobs (O). and bore a second hole (7* in. diameter), on center exactly 67- from the 7« in. hole. You'll now need to rout the curved slot in the swivel work support. There are several ways to do tins It you have a shop trammel outfitted lor your router (this can be as simple as a piece of 7« in. plywood, with your router mounted to one end and a nail as a pivot (Hunt on the other end I you can rout the slot before gluing the stiffener to ihe swivel work support. But this job is also easily accomplished on the router table.

First, mount a 7* in. diameter spiral bit (or a 7b in. diamelcr straight bit if you don't have a spiral cutter) in the router table. Then make a simple pivot block, as shown in Fig. 2. lo allow ihe subassembly to be fixed lo a pivot point. This pivot block is just a few scraps of plywood, with a '/■> in. diameter dowel extending down out of the lop block. Slide the subassembly over the 7» in. diameter bit. and clamp the pivot-poinl block to the router table. Turn the router on and gradually pivot ihe subassembly until the 67^ in. radius slot is completed to the specified length (mark the slot length from the full-size patient). Since you are making a full 7» in. deep cut (spiral bits, thanks to their aggressive cut and chip-clearing capacity should handle this cut easily), advance the work very gradually. If you don't feel that your router is capable of making a cut of

this diameter and depth in a single pass, you'll need to make the cut in several passes, raising the cutter about '/t in. each time. Clamp a slopblock to the lable lo limit the travel of the piece so all the passes will index to the same stopping point (you won't be able to see the bit until the final cut).

To complete work on the swivel work support/stiffener subassembly, mark and drill for the four machine screws (K) that mount the De-Sta-Co clamp (P), and drill out the back of these four holes and the top knob hole for the T-nuts (M). The 7-1-20 T-nuts require a ^s/i6 in. diameter sleeve hole and a shallow 7» in. counterbore for the head. Insert the T-nuts and mount the De-Sta-Co clamp. Then lake a 7* in. diameter drill bit and drill through the T-nut that you mounted in the machine screw hole for the top knob. By drilling out the threads in this T-nut. you've turned it into a bushing that wilt protect the hole from being worn out by ihe machine screw threads.

Next, drill though the base for the machine screws that mount the two knobs. An easy way to locate these screw holes is to first use a framing square to mark an index line, measure I 72 in. dow n from the top edge of the base to mark ihe first hole, and 6'/2 in. down from that point for the second hole. Drill these two holes, and for the iwo T-nuls that mount the machine screws, then insert the T-nuts. Insert the machine screws (ihe nuts lock the machine screws in position), mount the swivel work support/stiffener, large washers and knobs, and check that the swivel action is smooth. Also, bore out the adjuster block for the adjusting screw and T-nut, then mount it to the base (allow a little space between the adjuster block and work support, for adjustability). Insert a dry wall screw (N) into the edge of the swivel work support at the poinl where ihe adjuster screw makes contact. The head of the dry wall screw serves as a positive slop.

Assemble the remaining parts, using the connector and fence guide to join the brackets (the adjuster screw holes and T-nut counterbores should be made first, and the T-nuls mounted). Screw the rub strips in place, then mount the base to the brackets and base support. Use The Woodworker's Journal