Paterson's Worm Cubes

 

 

The theme of the sixth Gathering for Gardner conference (G4G6) was cubes (because they have six faces), and so I created about 200 clear acrylic cubes with pictures of worms layered inside them. This turned out to be quite an undertaking. To make things exciting I procrastinated massively, and didn’t even conceive this idea until a week and a half before the conference. A week was spent researching materials and testing various methods and tools, so the actual production process began Saturday afternoon and had to be finished by 5am on Thursday when I would leave for the airport. Fortunately I have some very good friends who contributed an awful lot of time in those five days – the whole project was probably about 120 hours of work. Which I don’t think I could have done in five days, even with a lot of coffee.

 

 

I won’t describe all the experimentation it took to figure out what materials and methods to use, but here is the final process:

 

Cutting the squares

The basic material for the cubes was 0.236-inch acrylic safety glazing, which I picked up at Home Depot. Each cube was a stack of six square slices 1.4 inches on a side. My housemate Tom has a table saw with a nifty sled that allows more accurate cuts with less risk to the digits than a normal fence. With some trial and error I fixed a thin fence to the sled to ensure a consistent width, and reduced nine 18x24in sheets of acrylic to 1.4-inch squares, about 1300 of them.

 

 

Sanding & polishing

I wanted the cubes to be clear on all sides, and that meant that the edges of each acrylic square, opaque after being cut on the table saw, had to be polished to a mirror finish. Tom had the bright idea of clamping them into his Workmate bench, which saved building a special jig to hold them during the sanding process. We could fit 8x24 squares at once, which meant we had to do seven batches, four sides each. Each side took about half an hour. Annie was the sanding champ – she took over and did all except part of the final batch.

 

Using a random orbital sander, the squares were sanded first with 60-grit to level them out and remove any gouges from the table saw, then with grits 120, 220, 1200, and 2000. The last two were wet-sanding steps – the surface was frequently sprayed with water to remove the dust produced by the sanding, which can be coarser than the grit on the very fine papers. Fortunately the sander didn’t seem to mind the water. You can’t get orbital sander disks with such fine grits, so I had to improvise by gluing a second layer of fine paper onto another disk. This had the benefit of covering the dust-catcher holes, so the water didn’t get sucked into the sander’s dust filter.

 

 

The final step was to polish the surface using a wool buffing disk attached to a drill. I used Meguiar’s Mirror Glaze Clear Plastic Cleaner No. 17, which did a great job of taking out the haze left by the 2000-grit sandpaper and leaving a nice polished surface.

 

Printing

I don't know of any easy way to get a color image directly onto rigid acrylic. It can be done: you glue laser-printed paper to the surface, face down, with a clear acrylic gel from Golden. When it's dry, you wet the paper and scrub it away with a sponge – the laser toner is plastic and would rather stick to the acrylic gel than to the wet paper. But inevitably some paper fibers remain, which is fine for an opaque background but not so good if you want a completely clear result, and it's very, very labor intensive. So I decided to print on thin, clear sheets, and sandwich them between the cube's acrylic layers.

 

Overhead transparencies, despite their name, are not very transparent. The six-layer cubes would require five images between the layers, and a stack of five standard transparencies is very hazy – I think one side is roughened to make the toner stick better. Calling around to the local art supply stores, I found Duralar, a completely clear polyester film which works in a laser printer. Just to maximize my fun, it doesn't come in 8.5x11 sheets. I ended up having to buy one 9x12 pad and a couple yards off a roll and cut them down to printer size.

 

 

I made three sets of five images, showing worms #060, #062, and #231; after each snapshot was taken I cleared the screen so that only new paths would be shown by the next slice.

 

 

I printed two sheets of 6x7 of each of these, which Annie kindly cut up with a paper cutter.

 

Drilling & Fastening

The six layers had to be fastened together somehow. Glue seemed too messy and slow, so I decided to go with some sort of fastener – two per cube, in opposite corners. That meant that each of the 1200+ squares had to be individually drilled in two corners – if you stack them up, the acrylic gets too hot in the center of the stack and melts, making permanent bumps on the surface that would prevent the squares from lying flat against each other. Bummer. My friend Carolyn was the drilling queen – she did six of the seven batches in three long evenings. The drilling produced an incredible number of curly white shavings.

 

The next question was what to use for fasteners. I tried hitting various nail-like things with hammers, which was fun but didn't produce anything that gave a reliable enough hold. You can get threaded aluminum tubes (a.k.a. standoffs) from places like Digikey, but even in bulk they cost about 60 cents each, and I needed 400 of them. That’s a lot of money to spend on hardware. After much experimentation, I found that if you hammer a wood screw into the end of an unthreaded metal tube it sticks pretty well. The cost of using screws was that one third of the squares (the top and bottom of each cube) had to have countersinks drilled so that the screws would lie flat. Fortunately Tom's drill press makes this merely tedious.

 

I bought all the hobby and art supply stores in town out of their stock of 1/8-inch brass tubing, and got 800 size 4, 1/2-inch brass wood screws with flat heads. Tom cut most of the brass tubing into short pieces on the table saw, using a neat jig he built to keep the tube from being thrown by the blade – you can sort of see it in the picture of the table saw above.

 

 

Final assembly

By early Wednesday evening, some 1250 acrylic squares had been cut, polished, drilled, and grouped into well-matched stacks of six, and over 1000 squares of Duralar with worm pictures on them had been cut. All that remained was to put them all together. No problem!

 

I threw a sweatshop party, and nine friends showed up to play cheap labor. Three teams of two, wearing latex gloves, peeled the protective backing off the acrylic squares, wiped all the sanding muck off them with anti-static cleanser, cleaned the fingerprints off the Duralar pictures, and stacked up the cubes ready to be fastened.

 

The remaining four of us actually hammered them together. We clamped each cube into some handy L-jigs that Tom made, tapped a brass tube through each of the two holes to punch through the Duralar sheets, and then hammered screws into each end. The first few took about 15 minutes each just for the hammering, which was a little alarming; but by the end of the night they were going fast and the record, held by Tom, was 51 seconds. We finished at about 11pm – no worries, 6 hours to spare!

 

I wish I'd taken some pictures of the stack of 200-some finished cubes – they made a pretty impressive pile. But here are a few of the finished products:

 

   

       

 

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