Tunable Tolerance Tetrahedron Twist Timewasting Toy

thingiverse

This printable puzzle toy was inspired by a design found on Thingiverse. The original design had a major flaw - it only provided an STL file with no option for adjusting tolerance or scaling. One of my students, Zachary Snyder, spent hours deriving his own formula in OpenSCAD to create a more flexible design. However, I soon realized that the puzzle could take an excessively long time to solve, especially considering its relatively simple structure. The 20160630 version has undergone significant improvements. The original design used a turn of 1.0, which caused compatibility issues with the new design unless the tenth_turns parameter was set to 10 instead of the default value of 12. Printer Settings: * Printer Brand: MakerGear * Printer Model: M2 * Rafts: No * Supports: Not Necessary * Resolution: Not Critical * Infill: Some * Notes: This puzzle can be printed as a single, intertwined piece without supports or as separate parts with/without supports. Using a brim is recommended when printing separate pieces. Tests have been conducted on two MakerGear M2 printers and one Wanhao I3 printer using PLA filament with extrusion heights ranging from 0.1mm to 0.25mm. The results show that the puzzle's thickness varies dramatically, making thin sections more fragile than thicker ones. Therefore, additional shells or infill may be necessary to improve durability when handling the puzzle. The 20160630 version defaults to having slightly thicker thin sections, which enhances strength. Higher dimensional accuracy prints have been achieved by printing the two parts separately using Slic3r-produced 10% 3D hexagonal fill and supports with 2 layers of shell. Important Stuff: Printing Intertwined: Believe it or not, this puzzle can be printed assembled without supports! The 75mm/side pink and blue examples were printed on two different MakerGear M2 printers, taken apart, and reassembled intermixed. Both prints required careful prying with a knife edge to break the minor welds caused by sag during printing. Printing Separately: Alternatively, you can get a nicer print by using a slicer to separate the two pieces and then print them with support to the bed and a brim to keep them stable. The second STL file was created using Cura for precisely that transformation (Cura's "Lay Flat" command is also helpful if you want to rotate one of the tetrahedrons). Printing the 20160630 one-part-at-a-time STLs produces remarkably clean and accurate prints. In fact, the only cleaning needed is snapping-off the support. Customizer Parameters Are In Microns: The Customizer still doesn't understand decimal input, so all the parameters to this design are given in integer microns -- 1/1000 mm units. For example, a good value for the gap is between about 0.25mm and 1mm, which would be obtained by setting Micron Gap between 250 and 1000 in the Customizer. Solving The Puzzle: If you print this as separate parts, you will undoubtedly be tempted at some point to just force the pieces together. DO NOT FORCE THEM. With a 1mm gap, the pieces are actually a DISTURBINGLY LOOSE FIT -- if you are putting them together the right way. Thing 186372 didn't leave a gap, so they talk about needing to sand the parts, but no sanding is required if you leave a gap (although you'll still want to file-off any remaining brim, support material, or hanging threads/stray blobs). What is the right way to put the two pieces together? Well, the version with the UK logo makes it a little easier to visualize, but the truth is that the simple spiral slicing doesn't line-up with the tetrahedron in one of the planes you expect it to. Once you find the right plane, it is a trivial matter of literally screwing the two parts together.