Solar Analemma Chandelier 2.0

Some years ago I built a solar analemma chandelier, using 364 addressable LEDs as the source of the light. It was a lot of fun and a real talking piece, but as a practical dining room light, it was far from ideal - it was not quite bright enough nor was the quality of the light especially good (to get a nice warm light you have to set it to almost yellow). So I have built a brand new one using 51 4W LED bulbs instead, one for each week of the year (the bulb at the crossover point serving two dates, hence 51 not 52 bulbs). Each bulb is the equivalent of a 40 W incandescent bulb, so it provides masses of (dimmable) light. It doesn't quite have the wow factor of the programmable LED analemma, but it is much more practical and still looks beautiful.

The solar analemma is the shape described by the sun when photographed over the course of a year at the exact same time of day and same location.* Because the Earth's axis is tilted and its orbit is elliptical rather than circular, it generates an asymmetrical figure of eight. And a beautiful one! This one mimics what the sun would look like if I took a photo at 12 pm every Tuesday of the year from my house.

* this is a tough photographic challenge! The first example was only recorded in 1978/9 by Dennis di Cicco (3rd photo above). The spectacular 4th photo above is Tunc Tezel's "Tutulemma": an analemma photograph that includes a total solar eclipse. More info on the solar analemma available here.

You will need either a 4' × 8' CNC machine OR a laser cutter, a jigsaw, and a router with a flush-cutting bit. When I made the last one, I had access to a ShopBot while I was an artist in residence at Autodesk's Pier 9 workshop. But I no longer have this access, so I adapted the design to a laser cutter. You will also need some plywood (1/2" and 1/4"), some formica laminate or edge-banding, wood glue, and whatever stain/paint finish you want for the chandelier. You'll also need some cables to hang the chandelier and 4 strings of 15 bulbs. And some replacement bulbs.

Larry McNish of the Calgary Centre of the Royal Astronomical Society of Canada made a spreadsheet that computes the layout for the analemma, and I used that and stretched the distribution of points so that it filled a 4' × 8' sheet of plywood. Happily, this stretching has the effect of separating all of the points to a reasonable distance in all directions. I took every 7th point starting from the crossover point and broke up the design into pieces small enough to be cut on the laser. The pieces would be used to generate a template that locked together like a jigsaw puzzle. But what made this idea work really well is that the template becomes part of the build! The Speedy360 I used had a bed size of 500 × 800 mm, but the longest pieces are less than 500 mm so most laser cutters ought to be able to handle them. The files are attached to this step in .dxf format. Cut them out of 1/4" (6 mm) plywood (I used 3 mm plywood, but in hindsight that was a mistake - see next step).

Lay the template pieces out on your sheet of 1/2" (12 mm) plywood using the picture from Step 1 as a guide, and glue them down with wood glue, holding them in position using weights. Make sure you thoroughly clean up any glue that oozes out. Once dry, cut out around the template using the jigsaw, leaving whatever margin that you feel you can safely cut to (a few mm = 1/8" should be fine).

Note: I used 1/8" and 5/8" plywood, but found the bulbs wouldn't quite screw in properly. I only found they didn't fit after finishing the build and hanging it up - I had to remove it, drill out deeper holes, refit the lighting harness and rehang. Yikes. If you use 1/4" plywood for the template, the holes will be the perfect depth.

The magic happens with the flush-cutting bit - clean up the nasty jigsaw cut with the router to leave a beautifully finished figure-of-eight. Your 1/2" (12 mm) plywood is now 3/4" (18 mm), and the template has become part of the build itself, which is really satisfying. Tidy up the internal corners of the figure-of-eight using a sharp chisel.

The lights have a collar that is accommodated by the laser-cut holes in the template. You need to cut slightly smaller holes in the 1/2" plywood. Use the circles you cut out with a central hole pre-cut to drill small holes to get the centers perfect, then from the other face drill 1 3/8" (35 mm) holes in the plywood using a Forstner bit.

With my original analemma chandelier I used maple edge-banding, but this time I wanted a black frame so wasn't worried about matching the materials, so I used some strips of laminate left over from building my kitchen counters. This worked really well - the laminate is plenty flexible enough but much stronger and stiffer than the edge-banding, and it didn't need any additional support (except for the crossover part, which I strengthened with some blocks, see photo). I glued it on the edge with construction adhesive and lots of clamps. I tidied it up with a flush-cutting bit in my laminate trimmer (a one-handed router). Some wood filler to fill scratches and seams, plenty of sanding and it was ready for painting.

I spray painted the chandelier with lots of light coats of black gloss paint.

I bought 4 sets of string lights, and chopped them up to get a more compact harness. Each join was twisted, soldered, and covered with heat-shrink tubing. This was pretty time consuming and I can't imagine doing it without some decent wire strippers. Pop a socket in each hole and screw the T-junction to the chandelier using the holes provided (I used 1/2" screws and some small washers). The sockets should fit fairly firmly in the holes but even if they're a bit loose, don't worry - the bulbs will hold them in position.

Suspend the chandelier using wire cable at several points. I used 6 hanging points and eye screws in both the ceiling and the frame. It is a hassle to get it level - I strongly suggest getting help! Tie it up at 3-4 points using cord and some helpers, use a spirit level or laser level to get it hanging perfectly, then add the adjustable wire cables. This kit has all the parts you need.

Wire the harness to your ceiling fixture (I used a pendant light cover) using pony tails. Add the LED light bulbs. If you don't already have a suitable dimmer, get one! You'll need it, 51 lights is WAY too bright for most dining room settings unless you're planning an interrogation or a photo shoot.

Enjoy your new light fitting, and make sure your guests appreciate the astronomical significance of that interestingly asymmetric figure-of-eight.

One of the neatest things about this chandelier is that it creates beautiful reflections everywhere in the room. On paintings, plates, wine glasses, eyes, you name it! All very cosmic.