"Before there were fidget spinners, there were twisty puzzles"
The Split 1x2x5 is a variation on Rubik's Cube, the 3D manipulative puzzle that took the world by storm in the early 80s. That puzzle is also colloquially known as a 3x3x3, each piece considered one unit of the cube. A 1x2x5 follows the same naming convention; the puzzle's dimensions are one piece by two pieces by five pieces. In this case, however, 8 of those pieces are "split" into two, in such a way that the puzzle not only remains stable, but also gains additional functionality.
Whereas a normal 1x2x5 only has 288 possible permutations, the "splitting" almost turns it into a 2x2x5, which is significantly more difficult to solve. To anybody who's interested, more information on this puzzle and it's classification can be found on its page in the TwistyPuzzles Museum.
I designed this puzzle in 2016, and first published it in 2017. The files can be downloaded later on in this instructable, or from Thingiverse.com. If you enjoy this instructable, make sure to vote for it in the Instructables InMotion Contest!
Step 1: Preparing the Files for Printing
If you don't have a 3D printer, you can use 3DHubs.com to get these files printed by someone near you! Remember to mention this instructable to them, so that they can reference it when printing, because I'll be outlining some specific suggestions for a better quality puzzle in this next step.
- Print "1x2x5x_5" x1
- Print "1x2x5Split" x2
First off, scale everything x27. I'm not sure why the files are so small, as near as I can figure I must have designed this in metric, but saved it in imperial, or something to that extent.
Orientation is everything when printing twisty puzzles, so follow the illustrations above exactly. While they might print faster in different orientations, I've found that these positions give the important bits sufficiently accurate clearances.
I printed these each at 0.1mm layer height, with 30% Honeycomb Infill, no support, brim or raft. You're free to mess with these settings if you'd like.
Step 2: Assembly
Assembly is fairly intuitive. The two non-split pieces act as centers, every piece connects back to these two. Lock sets of outer and inner edges together separately, as shown in images #4 and #5, then slide them into the center rails. Repeat x8, creating two separate, roughly identical halves (these should each look like image #1)
Turn each half on its side, and push the two together. I used a wood screw to secure them, but I've also posted an .stl for a pin on my thingiverse page, which can be glued into place. Make sure that there is some clearance between the counterbore and the base of the screw/pin's head, so that the two layers can freely rotate, while still keeping the whole thing together.
Step 3: Test & Sticker
Depending on the quality of your print, you may want to sand the internal mechanism to reduce friction. Once you've assembled the whole thing, turn both the vertical and horizontal layers by 180 degrees. Notice where it catches, then disassemble and sand as you see fit. The version that I used in the video had not yet been sanded, which caused the loud crackling and catches that you saw.
Once you're happy with the puzzle's turning, it's time to add stickers, and make this a real puzzle! If you scaled it properly, you should be able to use regular Rubik's Cube Stickers, which you can get here, here, or here. I had some leftover stickers lying around from my Rhombiminx, so I made my color scheme based off of what was available: that was, in this case, green opposite orange on the 2x5 faces, white opposite red on the 1x5 faces, and yellow opposite blue on the 1x2 faces. The square stickers were straight off of the sheet, the half-size stickers were made by cutting normal-sized ones in half and trimming the edges slightly.
Step 4: Solve It!
If you figure it out, let me know! I may have designed the thing, but when it comes to solving it I am yet to find a reliable method.