Introduction: Data Sculpture
This Instructable will go through the steps I used to make a series of plexiglass and resin sculptures based on personally recorded data.
I have made several of these so the images jump around from piece to piece but the process is the same.
Step 1: Data
All my art projects start with recording data. This screenshot shows one of my main tracking spreadsheets. Everyday I log miles traveled through various means. I use various apps, maps, and devices to get the info, but it all gets consolidated here in Excel.
Step 2: Drawing - Data to Surface
With a little messing around in Excel I can export points to Rhino. I usually use some kind of averaging to smooth out the data a little. In Rhino I build a patch through the points and trim the edges.
Step 3: Digital Surface to Machinable Surface
Once I am happy with with the surface in Rhino, it is time to construct the surface I want to machine.
This process is a little laborious as I am interested in creating a triangular mesh that looks equilateral from the top. To do this I set up a grid of vertical lines at the vertexes of the triangular mesh. Then I use the patch surface to trim off the ends of the lines. From the ends of the lines I create individual triangles to form the mesh.
In this example I am going for a 6x12in surface out of a 12x12x4in block of acrylic. I need to machine both the top and bottom of the surface for the final piece, so I flip a copy of the surface and joint it to the original. This way I can to all the machining with one set up on the CNC router.
Step 4: CNC Set Up
I export the surface I want to machine as an .stl file and open it up in Part Works 3D (ShopBot's 3D software).
The plexiglass is so heavy I just use a little bit of double sided tape and then block it in place on the deck of my CNC.
Step 5: CNC
The CNC process takes a pretty long time as I like to go pretty slow on the roughing passes to avoid chipping. I rarely go more than 1/4in. depth of cut with 50% overlap on roughing passing. The tool is a two flute 1/4in. ball end mill.
For the finishing pass I use the same end mill. It gives me all the detail I need even in the corners and set the passes at 1/100in.
Step 6: Sawing
Once the piece is done on the CNC I remove it and cut it to size.
Step 7: Resin Pour
I use strips of plex and solvent cement to seal attach the two pieces together with a small gap between them. I will pour colored resin into the gap to connect them and create the data surface. I build dams of clay on the top to prevent overflow. I use Smooth-On Epoxacast 690 with Smooth-On So Strong tints. With the resin mixed I put the cups in a vacuum chamber to get the bubbles out. The resin has a long pot life and cures completely in about 24 hours. I slowly pour the resin into the gap between the pieces so I don't introduce any more bubbles.
Step 8: Trimming
After the pour there is a bit more work to do before sanding and polishing. First I remove any clay dams or tape seals. Then I have to trim the plex seals away. If the piece is small enough I can do this on the table saw. If not I have to set up a surfacing jig and remove the material with a router.
Step 9: Sanding and Polishing
This step is really a bunch of steps...
Lots of grits of sand paper are required to slowly and carefully bring the surfaces back to a perfect gloss.
I use about 15 steps to go from 60 grit to the equivalent of 15,000 grit. Sand papers up to about 2000 grit and various pads for finer grits.
The whole process is done wet and by hand using a sanding block.
The resin and plexiglass have different densities so it is necessary to use a block to keep it flat. Power sanders would round the corners and dish the resin areas.
For the final polish I switch to Novus polish on a rag and sometimes allow a power buffer.
I haven't found too many ways to cut corners on this process. It just takes a lot f patience any scratch means backing up a few grits to make the correction.
Step 10: Finished!
After all that sanding it is really satisfying to finally see the finished product.
Here are a few of the pieces I have made with this specific process, and I am looking forward to making more.
See more images at: