Wooden Enclosures for Light Works

This is how I made the enclosures for a pair of artworks, the Scintillation Bar and the Star Atlas. Each piece is a wall-hanging wooden box with a front-facing acrylic panel on the front and enclosed electronics. As the artworks are similar in construction (yet different in aspect), I constructed both boxes at once, with identical dimensions. I was aiming a roughly 2 x 1 aspect ratio, that is twice as wide as high. For the long dimension I chose 12 inches making the short dimension 6 inches. This was roughly the size I was shooting for; the actual dimensions were determined by the largest pieces I could cut from the raw lumber, avoiding knots and imperfections.

I did my work in the Autodesk Pier 9 woodshop. I started with two Anigre planks, roughly 5" x 3/4" by five feet long. I chose this wood because of its lovely grain and the blond color. I planed a side of each plank with the Martin jointer and squared up a corner by by turning it 90 degrees and running it through the joiner again. Then I ran both planks through the planer to roughly the same thickness around 3/4 inch. The Martin planer is adjustable in increments of 1/1000 of an inch so this was not hard!

Because the two pieces of lumber were not the same width, I cut them down to about 4 1/2" wide on the table saw. I also cut the groove for the acrylic front panels. Experimenting with a piece of scrap, it turns out the kerf of the regular blade on the table saw was almost perfect to fit the 1/8 acrylic I would use for the front panel, so I didn't need a dado stack. Because I needed to groove all four sides of two boxes, I cut the grooves first in the two long pieces of lumber before cutting them down: much easier than grooving 8 shorter side pieces!

Next I cut the four sides of the two boxes from the long planks. Though I could have saved some wood by mating the miters (e.g. cutting AAAA/BBBB\CCC) I needed to keep the same side of the planks on the outside (because of the groove, which was already cut!), so I cut like so: AAAA\W/BBBB where W is a wasted area of knots. I set up a jig by clamping a mitered edge at the right distance for a side so they would all come out at identical lengths.

Once the pieces were mitered, it was easy to glue them up into two rectangular boxes. I added braces to the corners made from 1 x 1 stock. This was for several reasons: 1. the back panels need to be removable so this gives a surface to screw them into. 2. Braces strengthens the corner joints. And 3: I decided I wanted to screw (rather than glue) one of the side panels so I could remove it if I ever needed to fix or replace the front panel. After years of making things, I know how Murphy's Law tends to bite you the minute you remove the option to fix things. If I were to irreversibly glue the front panel into place, I guarantee you it would get scratched or cracked within days!

So I only glued two of the four corners of each box: I left one long side unglued, though I did glue all four braces; two of them accept screws that attach the unglued side. Note the blue tape on the square brace in the first photo: this was to stop any glue seeping from the brace sticking to the unglued side.

As mentioned in the previous step, each box has one unglued side attached with a wood screw through the corner braces. It was a quick job to countersink and drill two holes at either end of the loose side for the wood screws.

Because the artworks are battery powered, it's important to be able to easily remove the back panels to replace them. Since the back panels will be screwed into the corner braces, I was happy to find some brass threaded inserts so I could use machine screws rather than wood screws. These were easy to use; after drilling a 1/4" hole (using the drill press so holes are accurate and square), the threaded insert is screwed into the hole with a large screwdriver. This left a number 6 threaded hole precisely in the center of each brace, thus 1/2" away from the each edge of the back panel.

Once the boxes were completely cut and drilled, it was time to finish them. The planer and table saw left a fairly good surface but it's always nice to sand and polish to a final finish. I started with 320 grit sandpaper and a sanding block, then finished with 600 grit sandpaper and a tack cloth.

Though tung oil is my usual finish of choice, this was not available at the shop so I elected to use boiled linseed oil. I like oil finishes because they look natural, feel wonderful to the touch, and are easy to touch up with oil in case of dings or dents The final finish was boiled linseed oil rubbed into the wood with fine Scotchbrite abrasive pads, which is a superior substitute for steel wool. This squeezes the oil into the wood grain while smoothing it at the same time. Leaving the oil on overnight and rubbing the excess off with a rag leaves a wonderful silky finish. I only used one coat of linseed oil because I wanted the wood to stay blond and additional coats of linseed oil will turn yellowish. (Be careful with linseed-oil-soaked rags: as the oil "dries," the exothermic reaction with oxygen can cause the rags to spontaneously combust!)

The front panel for each work is a 1/8 sheet of acrylic. I laser cut each to the interior dimensons of each groove, minus 1/8 inch so it would slide in easily. Each panel has cutouts for optics, you can see the final results in my Instructables for each: the Scintillation Bar and the Star Atlas.