Popular Woodworking 2005-10 № 150, страница 42
Ingenious Jigs Mounting the Table When you use a drill press with an auxiliary table, the area under the bit invariably becomes perforated. So I included a replaceable section under the bit. This isn't a new idea, but I've added tricks that make mine better. It's nearly impossible to find 3/4" plywood that's actually 3/4", so I use two discs to match the "thinner" plywood. Before mounting the table to the drill press, use a 2V4" hole saw to cut two medium-density fiberboard (MDF) plugs from scrap material. One should be 3/16" thick and the other V2" thick. These two discs, used together, add up to 1^//16", which is much more likely to be the thickness of your plywood. Next, mark diagonals across the lower table to locate the center. Use a brad-point bit in the drill press to center the table and clamp it in position. Mark appropriate locations for bolts. Drill holes and counterbores for the bolts and re-center the table. Affix it with carriage bolts that lie flush or just below the top of the lower table. Now it's time to attach the two table halves. Remove the extruded channels from the upper table and lay it on top of the lower table. Move it back V4" from the front edge of the lower table and clamp it into position. Many drill press tables will use square table inserts, while I prefer a round insert because it collects less dust (no corners!). One concern with a round insert is if it was exactly centered in under the bit, the disc could get caught on the bit and spin. By making the replaceable center eccentric (drill through the disc off center), it cannot spin (an old engineer's trick). Install a 2V8" hole saw (lock-installing size) and drill through the first table until the saw edge just touches the lower table. Remove the plug. Move the top table to realign it perfectly with the lower table and re-clamp. I used two V4" dowels to keep the upper and lower table pieces aligned. They have no structural purpose and I placed them in the dados because the track covers them up. I didn't permanently glue the table pieces together as I have commitment issues. From the bottom, use screws to hold the upper and lower table together taking care not to drill through any of the T-slots. Apply a little glue to the bottom of the 3/16"-thick plug and drop it into the hole. After it has The two-plug system brings the insert flush to the table surface. Also notice the offset location (the through hole is where the bit will drill) to keep the discs from spinning. set, put a 1" bit into the press and drill a hole through the plug and lower table. You will see that the center of the plug doe s not match the center of the hole. Putting it all Together Reinstall the guide channels. Put the fence on the table and install the second T-track, and adjust to ensure smooth operation. Drop the V2" MDF plug into the table and cut T-track from the leftover 18" piece to fit from the back and front up to the edge of the plug. Install the T-track with screws. Next, using the center "groove" on the extrusion, locate the center of the fence and transfer a line to the front and top. Cut six pieces of T-slot filler stock to length (+ 3/4") to fit the table and slide into position. Next cut the four 163/4" pieces of T-slot filler stock for the extension guides. Glue the T-shaped stock into the extension pieces and attach the top piece. Adhere the scales to the fence and table, connect the lock-down knob and bolt on the fence, and you are set to go. Jigs, Fixtures, etc. The large T-slots require custom T-bolts. I make mine by using scraps of the T-filler strips. I drill a 3/16" hole through the center and then thread with a 14-20 tap. A countersink on the back lets me thread a V+-20 flathead stove bolt through to make a rock-solid T-bolt. Your fixture is ready, but I'm sure you'll continue to work on it, as I have. I've come up with a number of "add-ons" to improve the Roller guides are only one of the accessories you can add to your drill press table. usefulness of the table, such as a pair of roller blade wheels to serve as a rolling clamp for stock. And with all the T-slots available on the jig, there are lots of places to attach any kind of accessory you can dream up. PW SUPPLIES Lee Valley 800-871-8158 or leevalley.com 1 • slot-wall bit #16J60.61, $16.50 1 • 3/4" x 36" slot extrusion (H1) #1iK79.07, $10.50 1 • 48" T-slot extrusion (Hi) #1iK79.0i, $1 i.50 1 • i4" T-slot extrusion (H3) #HK79.01, $6.50 i • left-to-right adhesive scale (H4) #06K17.02, $i.50 1 • right-to-left adhesive scale (H5) #06 K17.01, $i.50 4 • V4-20 sliding T-nuts #05JH.15, $i.00 for 10 Rockler 800-i79-4441 or rockler.com 1 • V16-18 x iVi" T-slot bolt (H6) #83311, $.99 1 • V16-18 x iVi" T-slot bolt #33939, $1.19 1 • i" T-knob (H7) #71514, $.99 1 • 1" round knob (H8) #341i1, $1.39 40 Popular Woodworking October 2005 |
