Intro: Wooden/Magnetic Rubik's Cube
I made this cube as a wedding present for my good friend Dave. Dave and I are both what could be described as nerdy, and we are both fans of the Rubik's cube (although Dave's interest is closer to obsession than mine). This project was inspired by another Instructable, Magnetic Rubik's Dice Cube by burzvingion, which was in turn an adaptation of an earlier project by gfixler. A couple of years ago, Dave and I followed this Instructable together and made our own magnetic dice cubes.
At the time, I had recently developed an interest in woodworking, and I wondered if I could do something similar out of wood. I immediately recognized how hard that would be and threw out the idea. But later I realized a sufficiently momentous occasion might motivate me to try. When Dave got engaged last year, I knew I had to get to work.
Although I enjoy woodworking, I do not have a lot of experience yet. My interest would probably be a more developed hobby if I didn't live in New York City, with no access to a decent shop or tools. But that is part of the unique story of this cube. I did all of my work in the bedroom of my small Manhattan apartment (except for applying polyurethane at the end). The only power tools I had at my disposal were a cordless drill and a plunge router that I borrowed from my dad. I had to sweep up sawdust frequently, and I tried to only use the router in the middle of the day, for the sake of my roommate and neighbors.
I would love if people reproduce or adapt this project, but be warned that it is fairly tedious and time intensive. I estimate that I spent at least 100 hours on it over the course of last summer. That said, someone with more experience and more specialized tools might be able to do it much faster. I would love to hear comments from experienced builders on how the process could be improved.
I hope you enjoy my project!
Step 1: Materials
I wanted make each face of the Rubik's cube out of a different type of wood. I did some research about interesting exotic woods and ended up ordering this wood online from a scroll saw supplier. It came in boards that were 1/8" thick, 4'' wide, and 2' long, which was perfect for my purposes. Because I was ordering online and could not know for sure what it would look like, I got eight types of wood for possible outer faces. In the picture above they are, from right to left: lacewood, purpleheart, padauk, yellowheart, mahogany, zebrawood, cherry, and walnut. I didn't like the cherry or walnut as much as I thought, so I decided to use the other six. I also got four boards of Maple to use on all of the interior faces.
In addition to the thin boards, I needed base cubes to attach the various outer faces to. I ordered 5/8'' hardwood cubes online for a few cents each. You need 27, but I bought about 40 to allow for some defects and to have some for testing.
A total of 108 magnets are needed. I followed the strategy of burzvingion and used large D62 neodymium magnets for the connections along each core axis, so that the faces would pivot better around that axis when turned. 12 magnets are needed for this.
For the remaining connections, I used D42 neodymium magnets. These are a little stronger than the D32s used by burzingion and gfixler, because I wanted to make sure my magnets would hold through a thin layer of wood. I needed 96, but I got a pack of 100 and had a few spares.
The cube is primarily held together with woodglue; I used Titebond III. In addition, I used Liquid Nails clear silicone adhesive to bond the magnets to the wood before I glued the wood together.
The main tool I used was a plunge router. I used three different bits: 3/8" and 1/4" straight bits for drilling holes for magnets to fit into, and a 45-degree V-groove bit for cutting tiles that fit together into a cube. Other important tools were clamps and sandpaper.
I tested a few different finishes on the various types of wood, and I decided that Minwax Wipe-on Polyurethane looked the best. It was also the easiest to apply. I don't know what the long term affect on the colors will be, so I could only guess at that. Someone who really knows their finishes might have a better suggestion.
I used other random materials and tools, not for making the cube, but for making various router jigs. I'm sure there are many ways to do this, but I used some extra boards, nails, screws, glue, clamps, and a rubber band.
[Note: Unfortunately, the supplies for this project were fairly expensive. I spent about $80 on the wood with shipping, although I did have plenty of extra. The zebrawood board alone was $10. I also spent almost $50 on the magnets.]
Step 2: Basic Design- Anatomy of a Cubie
A Rubik's cube is composed of 3x3x3 = 27 smaller cubes, which are commonly referred to as "cubies". In this cube the cubies are independent objects that are held together only by magnets. The cubies are all slightly different, but have the same basic structure. In this way, the structure of the cube is very similar to the cubes by gfixler and burzingion. (I highly recommend that you check out those instructables if you haven't... they're well written, and this project builds on what they did. Also, they are much more manageable projects to start with if you actually want to make a cube).
The biggest difference between my wooden cube and its dice/acrylic predecessors is that the individual cubies are much more complicated. In the dice/acrylic cubes, a cubie was fairly simple: it was made by taking a solid cube, drilling holes from the outside, and gluing in magnets. But for this project the cubies can't be made from a single cube of wood, because they need to have different types of wood on different sides. So the cubies need to be built up from smaller pieces. I decided to make a small square tile for each face of the cubie, and glue them together into a cube. I used a smaller solid cube in the middle to glue the tiles onto. Notice that for the tiles to fit together cleanly into a cube with only one type of wood visible on each side (no joints or endgrain), they need to meet at 45 degree angles at each edge. This means the tiles need to be cut with a 45 degree bevel.
I could have made cubes in this fashion, from an inner cube and 6 tiles, and then proceeded as with the dice and acrylic cubes: drill holes from the outside and glue in magnets. But the additional structure of the cubie opened up an interesting possibility: I could put the magnets in between the tiles and the inner cube. If the magnets were close enough to the surface of the cubie, they should still be able to bond to the adjacent cubie. Having magnets embedded inside the wood has several advantages over gluing them from the outside:
(1) They are (hopefully) more secure. One problem I have with the dice cube is that I didn't use very good glue, and magnets pop out from time to time. Here the whole tile would have to pop off, and the wood glue on the whole surface area of the tile is very strong.
(2) I don't have to drill holes in the outer surfaces, so I can take advantage of the beautiful wood grain, even on the tiles that are facing the interior of the Rubik's cube.
(3) The magnets are completely hidden. I like being able to see the inner workings of the clear acrylic dice cube, but I also like the mystery of this wooden cube. Friends are baffled about how it works at first. Even once you realize it's magnetic, it still feels like magic to turn it!
So the magnets are embedded under the tiles. I drill holes in the tiles, but I drill them from the inside, and I drill them almost but not all the way through. This gets the magnets as close to the surface as possible while still being hidden.
Outline of Steps:
Now that the we have the design of the cube, here are the steps needed for constructing it:
- Cut the tiles. This step has two parts:
- Cut strips of appropriate width
- Cut strips into tiles
- Drill holes in tiles
- Glue magnets into tiles
- Drill holes in inner cubes
- Glue cubies together
- Finishing touches:
For this cube, I also had some special additions, which aren't really a part of making the cube:
- Woodburn a message
- Make a stand
Step 3: Make Strips
The first step in making the Rubik's cube, cutting wooden tiles, presented many challenges. The tiles needed to have precise and identical dimensions. They are very small, which makes them difficult to work on with power tools. And they needed to be made as quickly and efficiently as possible (I needed 168 of these tiles!). My solution was to use a router and a 45 degree bit, and use a jig to make controlled, reproducible cuts.
I won't give full step by step directions for making the jig, as I'm sure there are multiple ways to accomplish the same goal, but I hope the pictures make it clear how my jig worked. The main idea was to have two parallel boards on top which constrained the router to move in only one dimension. These were mounted on a base board, but in between was a layer of 1/8" thick wood (I used some of the maple, since I had extra) with a gap for the board that needed to be cut. After clamping the board in place, the router would cut a straight line perpendicular to the long dimension of the board, leaving a 45 degree bevel on the cut end.
The "gap" for the to-be-cut piece is formed by a length of maple on each side, and a small piece of maple on the end which determines how far in the board can slide. It is difficult to tell in the picture, but this small piece has a 45 degree bevel (facing down), so that after the first cut, the board can be pushed all the way in and the angled ends match up snugly. When another cut is made, the result is a strip 4" long, of the appropriate width, with bevels on either side.
This small stopper piece needs to be positioned precisely so that the strips are exactly the right width. This can be accomplished by careful measurement, and then trial and error to fine tune the width. The width can be fine tuned without moving the stopper by adjusting the depth of the router bit. I tried to minimize playing with the depth, though, because I wanted the gap between strips as small as possible so the grain would line up better.
Using the jig:
Once the jig was carefully calibrated, I used it to produce all the strips I would need. Later I would reconfigure the jig and cut the strips into three tiles each. I needed three strips of each of the outer woods (enough for one face), and I needed 36 strips of maple (enough for twelve faces). I made some extra maple strips to have spares for the next steps.
After cutting off the end of a board to get an initial bevel, the basic steps were as follows:
-Push board as far into the jig as it would go
-Clamp board securely in place
-Cut with the router. In practice, I would do several passes, plunging the router deeper each time (the maximum depth was always fixed)
-Remove newly formed strip
-Clean up the edges (the router often left a frayed corner instead of a clean sharp edge) with a few passes of sandpaper or scraping with a perpendicular blade
This was a tedious process, but I got faster as I went along. I was pleased with how well the jig worked and how mechanical the process felt by the end.
Step 4: Make Tiles
The next step was to cut the 42 strips I had made into square tiles. Fortunately, I was able to utilize the same jig with only slight modifications. The width-control-stopper piece at the end could remain unchanged. I now slid the strips into the jig lengthwise, so I added extra pieces on the side to hold the strip in place. These pieces were cut with a bevel on the end to fit snugly into the angled end piece, and also with bevels facing down on the sides to hold down the strip that was being cut. These extra side pieces were not attached permanently to the jig, but would be clamped under the cross-brace that the the strip slid under.
The hardest thing was keeping the strip secure. I could not clamp it directly, but often I would push it deeper into the jig with another strip from behind, and clamp that in place. In my first attempts, that was enough to hold the strip secure. Sometimes, however, the square would be loose once it was disconnected from the rest of the strip. This was a problem, since if the square rattled as the router bit passed over it, the router might take a bite out of the corner or cause the tile to crack. I eventually thought of a simple solution to this: I cut up a rubber band and glued it along one edge of the side piece which held the strip in place. This greatly increased friction and made it so the strip and tile would not move as the cut was being made. The piece with the rubber band was not permanently attached, only clamped, so I would move it out of the way to slide the strip in, and then clamp it back in place.
The process for cutting the tiles was similar to cutting the strips:
-push the strip all the way into the jig
-cut with router
-scrape/sand/clean-up edges if necessary
This step was time consuming and I worked on it over a couple of weeks. At my best, when things were running smoothly, I figured each tile took 3 minutes on average to make (combining the time to make strips and the time to make tiles). I felt pretty good about that, until I remembered that I needed 6 tiles per cubie, for 3x3x3 = 27 cubies. 3 minutes times 168 is a lot of minutes!
Step 5: Organize Tiles
Strictly speaking, this step is optional. You could just throw all the tiles in a big bin as you make them, or maybe a few bins sorted by type of wood. Then when you glued everything together you could just grab any tiles of the right type. However, I really wanted the grain to line up on each face when the cube was solved. I even aligned the grain on the interior maple faces, though those aren't visible unless you pull the cube apart.
The way I made the tiles, they came from right next to each other on the board, so I just needed to preserve the 3x3 grids of tiles that I cut and use each one for a face. To keep things organized, I laid out all the strips and tiles on my dresser. The top picture shows my progress about halfway through the process of cutting strips into tiles. I also came up with a labeling scheme and labeled every tile, just in case I tripped and spilled a bunch of them on the floor or something (fortunately that never happened, but the labels were still useful in planning which tile had to be glued where).
In my opinion, the extra effort was entirely worth it. The grain lining up across the faces of the cube is aesthetically pleasing and incredibly satisfying. It's one of the details that makes this project feel less like a homemade toy and more like a piece of art, a kind of functional sculpture. But maybe that's just me.
Step 6: Drill Holes in Tile
I needed a way to hold these tiny tiles still and perfectly centered while I used a power tool to drill a precise hole in them. Obviously it would be ineffective and completely unsafe to hold them with my hands. It was time for another router jig...
This one was pretty simple. On the underside of a 1/4" thick poplar board I had, I routed out a pocket 1/8" deep and the exact shape of one of my tiles. Right in the middle of this pocket, I also used the router to punch a circular hole all the way through. The idea was to slip a tile under jig into the pocket, where it would be firmly held down against the table. The hole would give me access to the middle of the tile, right where I wanted to drill the hole.
The next thing I had to do was get the router perfectly centered over the tile. I did this by trial and error. I used the v-groove bit because it has a sharp point, and plunged the bit down onto a tile (with the router off). I then rotated the tile 180 degrees and plunged the router down again. If the two marks I made lined up, I was centered, and if not, the true center was halfway between the two marks, so I adjusted appropriately. Once the router was centered on the jig, I fixed it there by screwing some pieces of scrap wood on three sides of the router base.
The last adjustment was to set the depth, using trial and error on spare tiles. I drilled as deep as I could so that the hole didn't break through the other side, and the thin wood remaining didn't break when I put a magnet in and banged it around a little. I would say the hole was about two thirds of the way through the tile.
Once the jig was set up, I churned through the 108 maple tiles pretty quickly. It is important to keep track of which diameter whole to drill. The center tile for each face holds a stronger magnet, and so they needed the 3/8" bit. Once all of the centers were done, I did the rest of the tiles with the 1/4" bit.
This short video shows the tile hole drilling jig in action:
Step 7: Glue Magnets Into Tiles
The most important thing is to glue the magnets in in the right way. Following gfixler's lead, I started by marking the same pole of each magnet with a black sharpie. This makes it much easier to keep track as you glue. [Caveat: One downside was that the sharpie ended up rubbing off onto the wood, and it bleeds in a little bit. I was able to sand away all the black dots at the end, but it was a pain. There's probably a better magnet marking strategy.]
The instructable by burzvington has a good explanation of the polarities, so I won't redo that here. It turns out, though, that at this stage you don't need to think too hard about it. I prefer to think about the wooden tiles as each being part of a 3x3 "face", even if it is a face that is inside the cube and not a colored exterior face. Each face has magnets oriented the same way (either all in or all out), and each face attaches to another face with opposite orientation. I was already sorting tiles by face to preserve grain patterns. So all I needed to do was glue magnets of a given face with the same orientation, and make sure I had half of the faces oriented one way and half the other.
To actually do the gluing, I just put a dab of Liquid Nail in the hole, pushed in the magnet, and clamped for a few minutes. I only had a few clamps, so I started pairing two tiles with opposite orientations. This way the magnets held themselves in place while the glue set.
Be sure to keep the tiles organized by face during this process. I had labels on the tiles, but it is much easier to keep them from getting mixed up.
Step 8: Drill Holes in Inner Cubes
Since the magnets and tiles are both 1/8", the magnets do not fit entirely into the holes (which don't go all the way through the tiles); they stick out from the inner side of the tile by a little bit. This means that to glue the tiles to the cubes, I needed to drill shallow holes in the cubes corresponding to each magnet.
This actually wasn't too hard, since once again I could adapt an earlier jig. The hole-drilling jig already constrained the router to be perfectly centered over the tile-shaped depression on the bottom. That depression was designed for a tile, but the cubes also fit in it and were fairly stable (since the smaller square face of the tiles is the same size as the face of the cubes). All I did was add a second 1/4" layer under the jig with a square hole that fit the cubes snugly.
With this jig, it was easy to drill centered holes in the faces of the hardwood cubes. Fortunately these holes don't have to be perfect and pretty. I set a depth that was deep enough, but I didn't have to worry about being too deep. The holes weren't always perfectly centered, but I accounted for this by drilling four times, rotating 90 degrees each time. The result was a hole that was maybe a bit big, but was centered. Here it is better to be a little too big and have some wiggle room for the tiles to line up well with each other.
The holes need to match the size of the corresponding magnets: The innermost cube has six big (1/4") holes. There are 6 adjacent cubes that have one big hole, four small holes, and one face with no holes. The twelve edge cubes have four small holes, and the eight corner cubes have just three small holes.
Step 9: Plan Tile Locations
Before I glued everything together, I took some time to think through which tiles should go where.
One decision was which type of wood should be on each outer face. This is pretty arbitrary, but I tried to to keep more similar colors opposite to each other. I also thought about how the grain should be oriented. I decided that whenever two faces met at an edge, the grain should meet perpendicularly. I also wanted opposite faces to have parallel grain. For the interior faces, I just made the grain go in the same direction as the faces they were parallel to.
A Note About Polarities:
It is important to consider polarity when placing the maple tiles. So far all I had done was make sure that six of my maple faces were oriented one way (we'll call it "N", although it doesn't matter if it is actually north or south), and the other six faces are oriented the other way (we'll call it "S").
In each direction, the cube can be cut by two planes, dividing the cube into three layers (see image above). Corresponding to each plane, there will be two maple faces: one on the central (tan) layer facing out, and one an outer (brown) layer facing in. All you need to do to make sure the polarities are right is to make sure that the faces on the outside layers pointing in are all "N" and the faces on the inside layers pointing out are all "S". This will ensure that magnets line up N to S regardless of how the cube is scrambled, since a tile on an outer layer will always be on an outer layer, and a tile on an inner layer will always be on an inner layer.
Step 10: Glue It All Up!
Finally the time came to start gluing cubies together. Until now, the project had just been an assortment of 297 tiny pieces spread over my dresser, and an abstract idea of how they fit together. Needless to say it was a little stressful to start gluing. I didn't know if things would fit together the way I planned (fortunately they did). I also was worried about making a mistake and gluing tiles in the wrong place (fortunately I didn't make any major mistakes). But in the end, it was really exciting to see things come together.
For each tile, if there was a magnet I put a dab of liquid nail on it (I'm not sure if this was necessary, but it didn't hurt) and wood glue on the rest of the inner surface
before placing it on the appropriate solid cube. At first I would glue opposite faces of a cubie, then after the glue dried glue another pair of opposite faces, and then the last pair. I eventually realized this was slowing me down, and not necessarily helping me align things better. By the end, I just slathered a bunch of glue on the tiles, put all six on at once, and mashed them around until they all lined up will and the glue seeped into all the cracks. I then held them in place by hand for a few minutes, and then switched over to clamps and wiped up the excess glue before it hardened fully.
The most important cubie to clamp well is the centermost cubie, since its six strong magnets are all opposing each other. For all the other cubies, they didn't need to be clamped for very long, and sometimes a rubber band would be enough to hold tiles in place while the glue dried.
Step 11: Assemble the Cube
As I glued the cubies, I put them together to form the cube. I started with the innermost cubie, then did the six centers which attach to it, then the edges, then the corners. I still needed to take the cubies apart to do more work (sanding and finishing), but I wanted to make sure that everything lined up correctly. It was also very satisfying to see the cube take shape for the first time.
Step 12: Sand
Although the cube was almost done at this point, it still required a lot of sanding. Each face of each cubie needed to be sanded (some more than others) to clean up any glue that spilled over, and to make the surface smooth and clean. That's 168 faces to sand. In addition to the faces, the edges of each cubie (that's 324 edges) needed to be sanded to round off the sharp right angles. Rounding off the edges on the outside makes the cube more comfortable to hold, but rounding them off on the inside is even more important--before sanding, the sharp edges would catch on each other and the cube wouldn't turn well.
I found the best way to sand these small pieces was to clamp a piece of sandpaper to the table and then rub the piece back and forth, rather than moving the sandpaper across a stationary piece. It worked, but it was slow and tedious process. I bet a power sander of some sort would have been useful...
Step 13: Personal Touch
I wanted to personalize this gift, but I was wary of doing anything to take away from the natural wood and the beautiful grain patterns. I didn't want to do anything on the outside of the cube. I decided to woodburn this on one face of the innermost cubie, so that it is only visible when the cube is pulled apart. I hope this cube is a keepsake that reminds Dave and Abby for many years of their wedding day, and the friends who got to be a part of it.
Step 14: Apply Finish
I wasn't sure what type of finish to use, so tested a few types. One straight oil, one oil based, and one water based:
Watco Danish oil
Minwax Wipe-on Poly
Minwax water based polycrylic
For each finish, I applied three coats to a spare tile of each color of wood and compared. I liked the oil based polyurethane the best. The Danish oil was good, but it darkened the lighter woods too much. The biggest problem was with the Zebrawood, where the darkening really decreased the contrast. The water based finish was more difficult to apply (brushed on vs rubbed on), and it did not leave a clean surface. It also looked more like a layer on top of the wood, which detracted from the natural feel.
I'm not positive that I made the right choice, since I don't know enough about finishes to know which will look better long term and protect the color of the wood. I had to pick solely on what looked the best now. I would be happy to hear comments from experienced woodworkers about what finish they would recommend for a project like this.
Step 15: (optional) Display Stand
A great way to show off a Rubik's cube is on a stand with a hole in the shape of an equilateral triangle. This lets the cube stand up on a corner and more sides are visible at once. A small plastic stand of this form often comes with a normal Rubik's cube.
I put this stand together with some 1"x2" poplar leftover from another project. I cut three small sections with 60 degree angles and joined them with box joints. There are many ways to make a triangular stand, though, so if you've made it this far in the project (or if you want a stand for another cube), I'll let you be creative and come up with the details.