I took a pause from experimenting with fixtures for building a simple acrylic box, but it’s time to revisit the topic. While thinking about the external frames I had built, I started re-examining all the basic assumptions I had held during those experiments.
One assumption was that I must design the fixture to stay clear of the joints, lest I accidentally bond the fixture to the box with a bit of overflowing glue. So I started thinking what it might mean if i intentionally wanted to bond the box to its fixture. The result is the “exoframe box’, a box with an external support frame that also functions as the construction fixture for the box during assembly. This prototype led to the following observations:
It is stronger. Once everything is glued together, the external frame greatly increases the strength of the box. This either allows a box to handle a greater load compared to an equivalent frame-less box, or allow the box to be constructed of thinner acrylic.
It allows non-square profiles. The external frame in this prototype is rectangular, but there’s no reason why it has to be. The external frame can add contours to meet functional or artistic requirements. Say, make a network data storage computer look like an elephant, as a play on the urban legend that elephants never forget.
It lights up very nicely. The external frame adds a lot of edges and corners, which add light paths to any LED lighting in the acrylic construction. A quick test with an LED confirmed that the “bling factor” went up dramatically.
It took quite a bit of effort to keep the kerf compensation math straight. It probably shouldn’t count, though, as I assume I’ll eventually figure out a way to have the computer deal with the kerf compensation math for me instead of keeping it straight in my head.
Increased complexity in assembly since we have 9 interlocking pieces instead of 5. Somewhat mitigated by the fact that the external frame assisted in alignment of the box internal pieces, just like fixtures are supposed to, but overall a box with external frame is still much less friendly to automation than a plain box.