Digital Woodworking: Table LampComments (0)
This article is from Issue 102 of Woodcraft Magazine.
Resin accents combine with a CNC-made shade that's stitched together
Lamps are fun to build. They go together quickly, require minimal material, and allow a lot of creative leeway. A few years ago, I developed a method for making shades from thin plywood, opening up even more design possibilities and a chance to break away from relying on commercial shades. After making a few of these wooden shades with traditional techniques, I switched to cutting out the pieces and routing the patterns with a CNC machine to take advantage of its speed and precision. In designing this lamp, I revisited that technique.
This lamp’s shade—a truncated pyramid—consists of four leaves with chevron cutouts that allow enough light to pass through to cast a warm glow throughout the room. I made the shade leaves from 1/8" cherry plywood and the base from ash. (See page 52 for more about this struggling North American native.) I’ve been playing with colored resin inlay lately and decided to incorporate a geometric pattern in the base. While not a reproduction, the lamp’s lines are reminiscent of the Arts & Crafts style. And while a CNC machine makes this project easier, you can be build it without one, using patterns available online.
Order of Work
- Make the base
- Pour the inlay
- Cut and stitch the shade pieces
- Assemble and finish
A stitched plywood shade atop a hollow, inlaid column
The shade consists of four trapezoid leaves of 1/8" thick plywood stitched together through a series of CNC-cut holes. Two half-lapped hardwood cross braces pinned to the shade hold its shape and attach it to the metal harp that, in turn, connects to the saddle under the socket. Grooves cut down the center of the two halves that make up the stem create a channel for the lamp pipe that houses the wire. Routed inlay adorns each face of the assembled stem. A chamfered collar and beveled plinth complete the base.
To C or not to CNC
While this lamp was designed to be made with the help of a CNC router, you don’t have to have one. You can make all the parts as shown with judicious templating and careful routing and drill press work. Find the full-size patterns for the shade and the stem inlay online.
Make and assemble the base
Mill a length of riftsawn stock to 13/8 × 27/8 × 20". Cut a 1/2" wide × 1/4" deep groove along the center of one face. Crosscut the piece into two 10" lengths and glue the grooved faces together to create the stem. After the glue dries, trim it to its final size, being sure to keep the groove centered. Rout the inlay on each face before filling the recesses with epoxy. After the epoxy sets, scrape and sand the faces. Cut the collar to size and chamfer its underside at the router table. Next, cut the plinth to size and bevel it at the table saw. Drill a through-hole in the center of the collar and plinth for the lamp pipe. Drill a 11/2" dia. × 1" deep counterbore in the plinth’s bottom face for the hex nut that secures the pipe. Center these pieces on the stem and screw them in place, plugging the screw holes in the collar.
Lock it down. Secure a fence and stop block to your CNC machine’s table with T-bolts. Add an opposing, inline toggle clamp to clamp the stem in place. Center a 1⁄16" straight bit on the stem’s upper face, then zero the machine. Run the Lamp Inlay toolpath file. Repeat the procedure for each side of the stem.
Scrape away excess. Fill one face at a time with epoxy. I used Alumilite Clear Cast with green PolyColor resin powder. After the epoxy cures, scrape off the excess and sand the surface through 400 grit.
Tilt and cut. Tilt your table saw blade to 21° and set the fence 1⁄2" from where the blade enters the table. For stability as you guide the cut on edge, clamp the plinth blank to a straight, 16" length of scrap that rides atop the rip fence. Bevel all four sides. Reset the fence to 8" and bevel the underside of all four edges.
Make and stitch the shade
Fasten the first shade blank to a spoilboard secured to your CNC table. Chuck a 3/32" straight bit in the router and center it on the blank. Zero the machine, and then run the Shade toolpath file. Repeat for the other three blanks. Sand the edges, rounding them to a bullnose profile before applying a finish (I used spray shellac). Once all four leaves are finished, stitch the corners together. Cut the cross brace pieces to size and notch their centers to create a lap joint. Bevel the ends of both pieces to match the slope of the shade. Then, glue them together at the lap joint. Drill a 1/4" hole through the center of this assembly to fit the harp. You may also need to drill a shallow 5/8"-dia. counterbore to accept the finial. Use a pneumatic pinner with 21 gauge, 5/8" long pins to install the cross brace about 1/4" down from the top of the shade. Attach toy wheels to the base to serve as feet. Apply finish to the base, masking the bottom of the feet to apply felt pads later. Then connect the finial and harp through the cross brace to create the shade assembly. Add the pipe, saddle, socket, and wiring. Finally, connect the harp to the saddle. Let there be light.
Tape it down. Use double-faced tape to fasten the shade stock to a 1⁄2"-thick MDF spoilboard that protects your machine table. Draw witness marks on the spoilboard to reposition subsequent shade pieces.
A stitch in time. String a single length of waxed linen thread through two needles. Starting from the inside of the shade, poke the needles through the bottom holes of two adjoining leaves, pulling the thread tight. From the outside, push each needle through the opposite hole, being careful not to twist the thread where they lie parallel. On the inside, cross the strands as you poke the needle through the next set of holes. Work up the corner in this fashion. Use enough thread (48" or so) to stitch 10-12 holes at a time, tying off the ends on the inside of the shade.
Put it together. Install the lamp pipe with the cord running up from plinth, and wire the socket as indicated in the instructions provided with the lamp hardware. Lastly, clip the shade, crosspiece, harp, and finial assembly to the saddle.
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