- First make a tile die design in expanded foam
- Then use evaporative (lost-foam) pattern casting to cast the tile die in aluminum.
- Clean up and shape the die with a grinder and other tools.
- Start cutting cans and stamping tiles
- Staple them into place on a ceiling, wall, or whatever you can think of.
Step 1: Make + and - Polystyrene Foam Molds of Die Plates
Make some foam cutting tools if you feel like it, a good sharp utility knife will do OK on this step. This link has a great variety of foam cutting ideas:
Polystyrene or styrofoam of some kind is carved into the shape you want to cast aluminum into. I used egg cartons, take-out containers, and dumpster scavenged foam. These foam pieces are exactly how the aluminum cast will turn out, so put some effort into this step.
First make two rectangular blocks out of the foam, about a half inch think and 8.25" by 3.75".
Print out a stencil or create your own for guiding and cutting a design on the 8.25" x 3.75" foam blocks. Here is this stencil link for use in Google Sketchup. If you make your own design, you'll want ribs of some kind as part of it to strengthen the tile. The templates I made have two squares which are the ribs. Cut the features into the foam very carefully with a sharp utility knife or exact o knife. The depth of the imprint should be shallow, about 1/16". A polystyrene egg carton is about the right thickness, a meat tray is too thick.
One foam piece should have an negative impression in it and the other should have the positive impression using egg carton foam (see picture). The two pieces of foam should have some wiggle room when assembled to make room for the thinkness of the aluminum can that will be pressed when the die is finished. You'll still need to clean up the final cast with a dremel tool.
Now finally hot glue on a foam sprue on the center back of the block; this forms a channel for pouring the molten aluminum into the cast. I used a 3" long piece about .5" x .5". In the pictures you'll notice two sprues/vents but these do not work, use a single center sprue.
Step 2: Put Foam Piece Into Dry Sand.
Before burying the actual foam pieces that were just carved, I recommend casting a couple of test pieces until you get the hang of casting.
In a metal canister or metal tub, fluff up some plain mostly dry sandbox sand that has been sieved with window screen. Press the foam mold into it the sand; then pack sand around the whole thing and bury it. Pat for a minute to reduce air pockets in the sand around the object. I added bricks on top of the sand to keep it packed tight.
Set a large metal soup can with both ends cut open onto the sprue; this is to funnel the liquid metal into the mold.
Step 3: Melt Aluminum
I'm not going to detail everything about casting here but I'll list some good links on metal casting and safety. Most importantly do this outdoors.
Casting Aluminum at submarineboat.com
BackyardMetalcasting.com ...Melting and casting metal yourself
Gather aluminum from everywhere; lawn chairs, stereo amps, computer hard drives, beer cans, lawn mower and weed trimmer engines. It'll take about a pound of aluminum per die half, melt down more than what you think you'll need.
Make a charcoal fueled aluminum melting furnace, link to my quick and cheap aluminum melting furnace setup instructable for details on the information below.
Using the 5 gallon bucket furnace, and depending on the amount of aluminum to be melted it can take from 10 minutes to 25 minutes to have a pool of molten metal.
The pictures below show a metal 5-gallon bucket, a piece of stove pipe, hair dryer, and some duct tape for cheap a foundry furnace. A hole is cut in the bottom side of a metal bucket to fit the stove pipe. The bottom of another metal bucket is cut off about 2 inches from the bottom; a lot of holes are punched in that piece and its inserted into the main bucket as a burning grate. Keep bucket lids, one lid should have a vent hole in it for burning and the other lid should be left unchanged for snuffing out the fire. The hair dryer needs to have the "cold" button taped to use it just as a blower; tape the dryer into the stove pipe.
For a crucible, a 14 oz propane bottle was used; the top was cut off and some bolts were added for grabbing the crucible with the tongs. I made some basic tools with some scrap steel from an old bed box spring. You'll need tongs for the crucible, some kind of shepard's hook to tip the crucible, and a plain rod with a little bend at the tip for poking things and skimming out the dross (impurities in the aluminum).
To operate this, fill the furnace 1/3 full with charcoal and light it like you're going to cook some hot dogs. Wait until the coals start to turn grey on the edges, now fire up the blower and set the crucible in there with chucks of the aluminum. Cover the furnace with the vented lid, then grab a chair, a drink, and wait. When the aluminum is liquid, skim the floaties off the top with a hooked metal rod until the molten aluminum looks like a shiny pool of mercury. Now it's ready to pour.
Have all the safety gear on, turn off the blower, remove the lid and use the tools to grab the crucible and pour.
Step 4: Pour the Liquid Metal
Like the last step, do this outdoors with good breeze, the stink of the plastic burning out of the mold is not too good for you.
Have everything ready with the foam mold and sand; also have a steel muffin tin or something similar for pouring excess aluminum into.
Pour slightly quick and aim well. This may take some practice with little chunks of foam before pouring the big project. Actually, I've recast the "big project" five times until I finally got the hang of casting.
Once poured, wait about five to ten minutes for cooling before poking at it. It will still be 500 degrees F or more; watch out it will be hot for about an hour after sitting. Use pliers to handle it. The sand also will hold this immense heat so don't start playing in it like I did, with a gloved hand (luckily).
Step 5: Clean Up the Cast
Use a wire brush, grinder, file, and dremel to clean up the cast. Remove little bumps and funny spots and cut the sprues off the casts. If you used styrofoam egg carton for the mold details, the depth of the positive die needs to be taken down by about half; also round the all the edges slightly. This might take a while until both casts fit together nicely with wiggle room. If there is too little wiggle room between the negative and positive die, it can act like scissors and cut or break the thin aluminum tile.
Step 6: Cut and Stamp Cans
First cut the raw material, the soda can.
This gets sharp, so wearing gloves is important. Use scissors or tin snips to cut the top off the can at the seam where the can bends. Cut down the center to the bottom and then cut off the bottom of the can. You should now have a rectangular piece of aluminum sheet metal.
Cutting lots of these little aluminum sheets in advance is nice
Lay a sheet in between the dies to make a little sandwich. Give it a few light raps with a ball peen hammer until you feel the deformation of the can. Open it up and see the tile; if you dies aren't perfect, this may take some practice and some dremel adjustments until everything works. Actually my stamp still tears and breaks the cans often, I think it has something to do with the sharp angles of the design.
Step 7: Install Metal Tiles
To cover an area, it takes about 4.5 can tiles per square foot. Install with a staple gun or something similar. Start from the end farthest from the entrance on a ceiling or start from the bottom when installing on a wall, this helps hide the overlapping seams.
Each little can isn't perfect, but when they're all installed the effect is nice.
Second Prize in the
Runner Up in the
Earthjustice United States of Efficiency Contest