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Ha. Ha. Just kidding. You may use aluminum. But you must euthanize your cube upon completion. With your bare hands.
Step 1: An Aluminum Weighted Companion Cube
This project is a 8"x8"x8" aluminum replica of the weighted companion cube from the video game Portal.
I made this miniature aluminum weighted companion cube on one of the manual mills at TechShop San Francisco. All the staff were super amazingly helpful. Without their help, this project would never have been completed. Thanks guys!
While I can't recommend that anyone do this on a manual mill, as it was super labor intensive, TechShop SF does have a sweet CNC mill (Tormach PCNC 1100) and while you can't do large pieces on it, all these pieces are not large.
As a manual milling project, I did learn a lot about manual milling, but it took basically forever to make. CNC mill highly recommended. I did this project with almost no manual milling experience. That means you can do it too. Especially if you have help from awesome TechShop employees. But make sure to get extra pieces so you can mess them up and end up with a sweet box of scrap aluminum when you're done.
As I can't recommend this be made in this fashion, this is not really a guide on how to make this particular cube. It is more of a record of what I did, and some notes and files that might be helpful to anyone making a similar project.
Step 2: Design
I wanted to make this as close to the actual in-game version, so the first thing I did was get the dimensions of everything. I tried to export the original 3D model from the Portal data files, but after converting the format, the 3D model was far too low-res either because I don't know anything about 3D model formats, or because the converter was incorrectly configured.
I gave up and bought the $9 version from Turbosquid. The model is high quality and seems to have all the right dimensions. I actually just used a screenshot of the model edge-on (with no perspective distortion) to measure out the features in pixels (using Photoshop's ruler tool), then converted those to inches based on the fact I wanted an 8"x8"x8" cube.
There may be some easier way to do this, so if anyone has ideas, let me know in the comments. I attempted to import the .3DS model from Turbosquid into Autodesk Inventor but had no luck. The newer, fancier Autodesk Inventor Fusion may support this.
After a bunch of making parts in Autodesk Inventor (free to use on TechShop computers!) I ended up with the Inventor files attached to this instructable. I tried to design the cube to be as close to the in-game version as I could get it, so there are no visible screws and only a seam on the back where the bottom of the cube slides off. The channels in the surface of my version of the cube (pink lines on the original cube) are built to hold EL wire, so the cube can glow pink as seen in the previous image if you look closely.
If you don't know Autodesk Inventor, don't worry, the program comes with great tutorials. I did these and then went to the free Autodesk class offered by TechShop. But I already knew more than the class covered because the tutorials are awesome. Do the tutorials and you'll know what's up.
I haven't included any of the derived drawing files, since they are not up-to-date and didn't include all the relevant dimensions anyway. You're probably better off making your own with the dimensions you need displayed. Having these printed out is super helpful. I ended up marking mine up with calculations of distances on the surface that I forgot to write down (see image).
Step 3: Prototype
The design calls for 6 face plates, 6 circular pieces for the hearts, 8 corner guards, and 12 edge guards. Before attempting to make the cube, I made a prototype or two of each piece. I got all of the metal from OnlineMetals, I don't know if it is competitive vs local metal shops, because I could never find any sort of price list for a local metal shop. For quantities and pieces this small, it is probably not too bad. They offer a discount if you order > $100 worth of metal, and there are sometimes coupon codes available.
Keep in mind that when you order the metal, you want a bit of extra material so you can pretty it up before cutting. The extruded aluminum has an ugly finish that you probably don't want and will need to remove. Also, if you request it cut to 3 inches, sometimes you get 2.9 inches, so always oversize by a bit.
Here are the pieces I used:
Face Plate: Aluminum 6061 0.25" Plate, 8"x8"
Circular Piece: Aluminum 6061 Extruded Rectangle 5"x0.5" cut to 5"
Corner Guard: Aluminum 6061 Extruded Square 3"x3" cut to 3.25"
Edge Guard: Aluminum 6061 Extruded Angle 2"x2"x0.25" cut to 3 ft
I would recommend larger pieces for the circular ones, or just use circular stock and make it on a lathe. I used the mill because I had not taken the lathe class at TechShop, so I couldn't lathe anything.
Step 4: Face Plate
This part is the most straight forward to make, but there are 3 different variants in this cube, the "Top Face" which is the part that opens, the "Back Face" which has space for the "Top Face" to slide over it, and the "Normal Face" which is for the other 4 sides of the cube. Technically the "Top Face" should be on the bottom of the cube because it does not have EL wire run through it like the other faces do.
Here are the steps I used for making these:
1) Place plate flat in vise (I had to reverse the jaws to fit them initially, most vises let you move the jaws onto the outside to fit larger objects)
2) Machine all edges down to specified size. For the Normal Face this is 7.5"x7.5"
3) Mill channels on the outside...side. On these plates I used a 0.125" bit, at a depth of 0.125".
4) Mill the cross area in the middle, this is so that the EL wire is not bent too sharply. I didn't mill it as drawn since I was using a manual mill. Instead I just made a square in the middle of each face, 0.125" depth.
5) Drill all holes. I used a center drill first so that the drill bit didn't wander. These holes are all sized for #8-32 screws, which is the only type of screw I used in this cube. Don't drill holes into the vise. I made these holes pretty accurate, as there is not a lot of room for mis-alignment in my design.
6) Counter-bore all holes on the inside side of the plate. This is optional for all plates except the "Top Face" which must be counterbored enough so that the screws are flat on the surface (since it slides across another plate to open)
6) Cut the u-shaped holes on the edges. These are more gaps for the EL wire to run around the cube. I just used a properly sized end mill and ran it straight into the side of the plate.
7) Cut the 45-degree corners on the edges of the plate, I mounted the plate flat on the top of the vise, turned 45 degrees. I used v-blocks to hold the plates in place. There may be a safer way like mounting them on the table directly. The important part is that the plate is now 45 degrees to the y-axis of the mill, and you can just move the mill along that axis to get a nice 45 degree cut on the corner.
8) Chamfer the edges to 45 degrees. This is hard to do quietly. I ended up mounting the plates vertically in the vise with 2-4-6 blocks like this sweet picture. Combine that with a 45 degree chamfer mill bit, and bam. Faces done. I also chamfered the outside just a tiny bit, like 1/32" so that it wasn't sharp.
Step 5: Circular Piece
These pieces are arguably easier than the face plates. If you have a lathe, that's probably a better idea than doing it this way.
I faced the piece so that it would be all pretty. I used a face mill for this (borrowed from TechShop). Some experimentation with different feeds and speeds should get you a decent finish. Make sure your mill is in tram (not tilted relative to the table) or the finish will suffer. I also squared up the piece first so that I didn't have to worry if things were all parallel.
1) Mount a rotary table on the mill and center the mill above the table. A "wiggler tool" is useful for this, but the precision for this piece is not terribly important.
2) Mount the square block on top of a sacrificial layer (so you don't accidentally cut into the rotary table) on the table.
3) Rotate the workpiece while cutting at the proper radius with an end mill (taking into account the width of your cutting tool). Be careful not to cut all the way through the piece will fall out and then you can't do the next step.
4) Rotate the workpiece while using a fillet cutter to get the radiused edge.
5) Use a vertical bandsaw to cut the thin layer of metal you left around the circle
6) Finish up the edge left over from the bandsaw. Some grinding may be appropriate here.
7) Drill the holes in the back. Easiest way I found to do this was to mount it in the vise with parallels underneath. Then use an edge finder on the left and then the right side of the circle, divide by two, and you have the x-axis center. Do the same for the y-axis and you have the center of the circle. You can then find the 4 hole locations, just don't rotate the piece before you finish drilling.
8) Thread the holes using a tap. I did this by hand and created a guide (see image) so that the threads wouldn't be crooked. This was just a scrap block of aluminum with a close-fit hole through it, so I could hold it against the circle piece and the tap would not tilt. Tap magic is amazing. Use it. I wear gloves though since it feels burny.
Step 6: Edge Guard
I got one long piece of angle bar and cut it down into 12 pieces with the horizontal bandsaw. I then finished up all the faces and cut out the radiused inside corner with an end mill. The outside faces and edges I got with a face cutter (like a fly cutter but faster), the inside I used an endmill, since nobody can see the milling marks anyway.
1) Mount the rotary table on the mill and center the mill over the table. Tilt the head to 55 degrees (so that the chamfer you cut will be 35 degrees), this will mess up the x-axis zeroing, but the y-axis zero will still be good.
2) Have already made a sweet fixture plate (see image) to hold the angle bar pieces at the proper radius and just put that on there. I would recommend at least a 0.5" plate, not the 0.25" plate you see in the image.
3) Load each angle piece into the fixture plate, make a few passes until you have cut the radius completely, flip it over and do the other side.
5) Tilt the head back to 0 degrees.
4) Cut the large 45 degree chamfer on the edge. I put the edge piece in the vise and used a 45 degree chamfer cutter.
5) Cut the small 45 degree chamfers on the outside of the radius. I made a setup involving v-blocks in the vise to hold the piece at 45 degrees (see image), then used a 45 degree chamfer cutter to cut.
6) Drill and tap holes. I put it in the vise with some parallels. Be careful not to drill all the way through, it's only 0.25" thick. I couldn't fit a center drill in there, so I used a transfer punch with a block I made to align the transfer punches (see image).
Step 7: Corner Guard
These corner guards are made out of 3"x3"x3" blocks, with the inside hollowed out. I squared all the blocks and faced the 3 visible faces on each.
1) Drill and tap 3 mounting holes in each block, on the 3 ugly (not faced) faces of the cube. These will be cut away later, so it doesn't matter. I made these about 2" deep.
2) Mount the block to a fixture plate (see image) and then to a rotary table, tilt the mill head to 45 degrees (see image).
3) Make multiple passes with a large end mill set to a depth of greater than 0.5 inches until you have the desired radius.
4) Repeat for the other three sides (see image) and return mill head to 0 degrees.
5) Hollow out the inside of the block with a short end mill (~1" cutting edge) on each of the 3 ugly faces.
6) Hollow out the remaining area using a long end mill (~3" cutting edge) on each of the 3 ugly faces (see image). You will end up with a large pile of aluminum on the floor.
7) Chamfer all edges. I didn't have a 45 degree chamfer cutter large enough, so I used an end mill with the workpiece mounted at 45 degrees in the vise.
8) There are four chamfers left to do on the corners, these are, it turns out either 55 or 35 degree chamfers depending on which surface you measure from. Mount the corner brace in the vise at a 45 degree angle, then cut the chamfer with the mill head tilted to the proper angle.
9) Drill and tap the 3 inside holes.
Step 8: Assembly
I drilled and tapped and counterbored all my holes to use these #8-32 1/4" socket head cap screws. I used around 100 of them total, counting ones I lost. On this design there were also two 1/2" screws of the same type used for the latching mechanism. The latching mechanism proved unnecessary since the lid is very hard to get off.
While assembling, I ran a 7ft length of pink EL wire (2.3mm) around the cube. It was just long enough to cover all the faces except for the lid face.
Step 9: Final Touches
Unfinished aluminum is pretty soft and scratches. It would have been a good idea to anodize this piece, but it's primarily a decorative piece and I didn't know any anodizers, so I just left it as is. It does have a number of scratches on it now though. For the companion cube this just gives it character.
I originally had a manually activated EL wire inverter inside the cube. I replaced this with a QT100 chip, some extra circuitry, and nylon screws to make one of the hearts a capacitive touch sensor insulated from the rest of the cube. But then the batteries leaked everywhere and so I removed it. The capacitive touch sensor was definitely the way to go, but in the future I will put batteries inside some sort of leak proof case.
The hearts are made on TechShop's vinyl cutter and just stuck on. Vector file attached.
The red text on the aluminum plates cleans up with some acetone and a bit of scrubbing.
Included is a picture of my brother, who got this cube for christmas. He can't figure out how to get it open.