In First Tech Challenge robotics, robots must fit inside a cube with eighteen inch side length to be elgible to compete. What better way to test this than to build an 18x18x18 box and see if the robot fits?
This sizing cube was designed to be lightweight, low-cost, and highly accurate. I purchased 40 cubic feet of 5/16th inch thick plywood for $30 at a hardware store, as well as some aluminum extrusion to give the box an industrial look.
I CNCed interlocking flanges into the sides to hold the box together using a ShopBot milling machine, and milled partial pockets onto the faces as well to reduce weight. While the flanges would be sturdy enough to hold the box together on their own, I also used a nailgun to affix the sides together and glued some aluminum extrusion to the sides for aesthetic purposes. Ultimately, the box (without the aesthetic aluminum extrusion) weighed 9.5 lbs.
To make this yourself, download the DXF files and load them into your preferred CNC machining software (I used Aspire). Be sure to mill out the corners inside corners completely using a dog-bone cut.
The finished product
CAD model of the front face of the box
CAD model of the box with some aluminum extrusions hidden
