CNC Plasmascreen Coffeetable
Being a university affiliated FabLab has some perks: we get to pull useful items from University Surplus (one department upgrades their computer lab, other departments call dibs on the old hardware, sometimes really new stuff, sometimes really old stuff).
Nearly all of the computer equipment at CUCFabLab was pulled second-hand this way, then topped off with RAM and upgraded to SSDs. A funny assortment of other supplies end up getting collected: decades old oscilliscopes, a 1980s bandsaw, and this big old 60″ plasma screen display.
It weighs about 100 pounds and is fairly low resolution (not quite 720p if I remember right) and it took up an awful lot of table space, so it quickly got basemented. That was until my Fab Academy assignment was to ‘make something big’ and I remembered that I always wanted a coffee table that was a giant computer screen.
The neat thing about plasma screens is that a lot of the electronics are bonded to the glass (tho I can’t recall where I heard that…) and as a result, they often have a pretty thick slab of glass to start with, so it’s sturdy enough that I don’t feel nervous about setting my laptop and maybe a cup of coffee on the screen (tho a spill of the latter might be fairly disastrous if you don’t contain it before it drips into the edges…).
Putting a big slab of acrylic or glass on top of a large display is often the most expensive part of this kind of object, so avoiding that part altogether meant I just needed a cheap MDF base for the TV to sit on. Like most TVs, there’s the front body of the screen that tries to be thinner while the power supply and mainboard sits in a sort of hump on the backside. So the design of a base that goes up to this edge but leaves room for the hump turns out looking like a pool table.
It was designed using the Rhino plugin Grasshopper, which proved to be a very intuitive interface for parametric design. It is a matter of dictating the size and position of 3 rectangles (the top of the table, the base of the table, and one that can be scaled and moved as a midpoint) and then creating “lofted curves” through each set of corners. This is an automatic function that creates the whole smooth shape pictured without any work on my part. I get to just change the position of the midpoint of the curve until I like the look of the resulting curve. Then I just subtracted a box with the inner dimensions I needed from the larger shape.
After that, I have a program to do the work of planning my assembly as well. The free 123D Make by Autodesk has a great workflow to open your 3D file, type in your material parameters (“I’m using 4′ by 8′ sheets of material 1/2 inch thick”)
I got the pieces cut at the architecture lab with lots of help. I learned that with this slotted construction technique it’s necessary to drill holes at every interior corner (so in the CAD file you select each of these corners and create ‘points’ on a separate layer to export as a drill file). This was about $40 worth of MDF and took less than an hour to cut out on Architecture’s giant fancy CNC machine.
Assembling it took a lot longer. Lots of rubber malleting.
I started playing with processing sketches (like the rainbow above), but it takes up a lot of space and there’s not a good spot for it at the lab, but the TV is unvierstity property so it can’t be taken off campus, so it is hidden in a corner — the interactive processing sketches will wait for now.