A comment on my last YouTube video pointed out that the SL(2,3) group expressed by the Quaternion Cube is isomorphic to the group formed by multiplication of the unit Hurwitz quaternions.
Simulator
‘Order’
There are five different orders of unit Hurwitz quaternions: 1, 2, 3, 4, and 6; On the puzzle, the order represents how many times a sequence must be repeated to return to where you started.
The Quaternion Cube is a rather easy-to-solve puzzle that I designed to visually demonstrate the Quaternion Group Q₈.
The puzzle turns over the top 4 vertices of a cube, with 1:2 gearing connecting the opposing corners. There are linear slides under the edge pieces that prevent the static corners from blocking the overall movement.
The puzzle has 24 possible positions, which express the group SL(2,3). SL(2,3) contains the Quaternion Group (Q₈) as a subgroup, and these Q₈ states are expressed over the 8 edges whenever the corners are solved.
STL Files: https://quirkycubes.com/public/QuaternionCube_STL.zip
Sticker Template: https://quirkycubes.com/public/QuaternionCube_Stickers.eps
Hardware required:
- 5x M3 Springs (~10mm uncompressed)
- 5x M3 Washers (6.9mm dia)
- 5x M3 x 16 Screws (button or socket)
- 12x M2 x 8 Button Head Screws
- 8x M1.6 x 16 Socket Head Screws
- 7/64" drill bit
I printed my copy out of ABS and vapor-smoothed it to post process it. I don’t see any reason that it wouldn’t work in PLA, but you will need to sand the edge hooks a little to get smooth motion. Here are the settings I use on a Bambu P1S:
DoDot M12
The DoDot M12 is a twisty puzzle that mechanically demonstrates Mathieu group M12. It’s a modification of my original vertex-turning dodecahedron where sets of three turning axes are geared together internally. This gearing was chosen to greatly reduce the number of possible permutations of the ‘dot’ pieces, which behave according to the rules of the 12-element M12 permutation group. The edge pieces of the puzzle behave as 6 disjoint orbits of 5 pieces, which makes them easy to solve. I greyed out the petals to avoid making the puzzle too complicated.
DoDot Puzzle
The DoDot puzzle is a variation of the Bauhinia Dodecahedron inspired by David Pitcher’s OctaDot.
Antler Cube
The Antler Cube is a modification of the Nón Lá cube that unlocks new moves and a more difficult solve.
Glaze Material Substitutions
This page provides a set of calculators to help with calculating common material substitutions in glaze recipes.
Warning: These calculators are based on theoretical UMF analysis of the materials, and I have not verified them experimentally. Oxide analysis isn’t the only factor that determines how a material will behave in a glaze.
Each calculator allows for conversions between two material forms. Click “Switch” to toggle the conversion direction. Red cells indicate that a material should be subtracted from the recipe.
Wrapping vector artwork around a conical object in Inkscape
Free vector editing tools are pretty lacking in intuitive ways to wrap a template around a conical object (i.e. mug or vase). I aim to produce a vinyl decal that can be applied perfectly to a ceramic piece without any stretching.
This post is not a step-by-step procedure, but rather a general overview of the steps that I use to fit vector artwork to pieces of pottery using Inkscape and a vinyl cutter.
Miscellaneous pots 2023-2024
Current development builds for KiCAD 7 include the new constraint keyword physical_hole_clearance for detecting hole and pad collisions within a common net. This is useful for detecting via-in-pads which are often undesirable, as some PCB vendors upcharge to plug vias that could cause wicking during assembly.
To set up the custom design rule, first install a nightly build of KiCAD (6.99). Please note that saving a project with a development version of KiCAD will prevent older versions from opening the PCB file. To prevent this, I run the DRC from KiCAD 6.99 and make the necessary changes from KiCAD 6.
