Face Turning Octahedron Puzzle

This model requires support material, and it is important that the undersides of the floating areas are clean, so I highly recommend using a dedicated support material for the interfaces.

OpenSCAD file is included for the brave who want to make modifications, but note that there was no effort put into cleaning it up for other people to use.

Printed parts list:

Internal color
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4  antiaxis.stl
4  axis.stl
24 center.stl
1  core.stl
12 edge.stl
6  inner_corner.stl
6  outer_corner.stl

Each outside color (Double if using only 4 colors)
--------------------------------------------------
3  center_facet.stl
3  corner_facet.stl
3  edge_facet.stl

Non-printed parts list:
It is recommended to get extras. I included the part numbers I used from McMaster, but other options may work.

4   M2x16 Screw         91290A047
6   M2x20 Screw         91290A049
10  Compression Spring  9657K263
16  M2 Heat-Set Insert  94180A312

Magnets:

144 N42 1/10" dia x 1/16" thick magnets   DH11 from K&J

Extra parts for assembly:
2  magnet_jig.stl (Note: The STL has two separate objects. Separate them in your slicer before printing. Only the bottom half needs to be printed twice.)
2  N42 1/10" dia x 1/16" thick magnets
Super glue
Weight 5 silicone lube
Blue threadlocker fluid
Sharpie or other marker that can write on plastic

Assembly instructions:

Section 1: Inner mechanism assembly

1.1  Install heat set inserts (4 total) into the legs of the core. After each installation, thread an M2x20 screw all the way through the core so that it pokes out the other side to remove any plastic that flowed into the hole. GO SLOW WHEN TURNING THE SCREW. Going fast can cause the screw to get stuck inside the piece and you'll need to start fresh.
1.2  Install heat set inserts (6 total) into the inner corner pieces. After each installation, thread an M2x20 screw all the way through so that it pokes out the hole on the other side.
1.3  Attach the axis pieces to the core with an M2x16 screw and a spring under the screw head. For now, don't tighten too much.
1.4  Insert the inner corner pieces and the antiaxis pieces between the axis pieces to form a spherical skewb.
1.5  One by one, unscrew the axis pieces to apply threadlocker, then screw them back in. I found that with the small size it was easier to apply the fluid to the insert rather than to the screw.
1.6  Tighten screws to desired tension.
1.7  After the threadlocker is cured, add weight 5 between the pieces and turn the puzzle a lot to distribute the lube so that it turns smoothly. It is crucial that this inner mechanism turns well. If you notice any pieces that tend to catch on other pieces, trim the catching sections now.

Section 2: Magnet installation

Be sure to give time for the superglue to cure as appropriate between steps.

2.1  Superglue a magnet into the bottom part of a magnet jig.
2.2  Using the first magnet jig, use it to superglue a magnet into the other magnet jig in the other orientation.
2.2a Put the top piece of the magnet jig over the bottom piece.
2.2b Put a magnet over the top piece. It should be held on top of the nub by the magnet in the lower piece.
2.2c Apply a small amount of super glue to the top of the magnet to be installed.
2.2d Press the magnet into the desired position with both pieces of the jig.
2.2e Remove the bottom piece of the jig, holding the top piece in place.
2.2f Remove the top piece. The magnet should be installed.
2.3  Mark one jig with a triangle and the other with a square.
2.4  Use the square-marked jig to install magnets in the outer corner and edge pieces (4 in each piece), following the procedure in steps 2.2a-2.2f.
2.5  Use the triangle-marked jig to install magnets in the center pieces (3 in each piece), following the same procedure.
2.6  Allow glue to cure.

Section 3: Outer mechanism assembly

3.1  Attach each outer corner piece with an M2x20 screw to an inner corner piece, with a spring under the screw head. Don't tighten too much, but the spring should hold the outer and inner corner pieces so that they touch.
3.2  Insert the center and edge pieces.
3.3  Tighten corner screws to desired tension.
3.4  Apply lubricant to the outer mechanism as desired.
3.5  Press facets into the corresponding positions on the outside of the puzzle. Note the slightly different shapes of the facets for the different types of pieces. If a facet is too loose, secure it with a bit of superglue, but note that this can cause corner screws to be more difficult to access.

Printing Recommendations:

For mechanism pieces (everything except facets and magnet jig), print with a support material and 0 top spacing on the support interface.
I used PLA as the main material and PETG for the support interface. As PLA and PETG need different bed temperatures, for pieces that want supports near the build plate due to the shallow chamfers, I used a raft so that only PLA would touch the build plate.
Ideally, use a support material that can be printed on the same bed settings, so that the first layer of the piece can utilize the surface finish from a smooth build surface.

Use as small of a layer height as you have patience for. I used 0.12mm layer height with a 0.2mm first layer.

Using a textured build plate for the facets puts the texture on the outside of the puzzle and gives it an amazing look.

Recommended Orientations:

These orientations try to make the supported surfaces as horizontal as possible to minimize the number of material changes needed.

Core - With one leg facing upward.
Antiaxis - With one side of the triangles facing the build plate. This makes the contact with the bed extremely small so a raft or brim is recommended. If using a brim, cut off any elephant's foot as best as possible, as that is a likely source of catches.
Axis - With one side of the triangles facing the build plate.
Center - With the side that goes next to the adjacent corner piece facing the build plate.
Edge - With one of the magnet holes facing the build plate. This makes the contact with the bed fairly small, so a raft or brim is recommended.
Inner Corner - With one of the short sides facing the build plate.
Outer Corner - With one of the outer faces facing the build plate.

Possible Future Improvements:

* Corner-to-core magnets
* More material on the core to make it easier to print and install threaded inserts. The legged version came from a development iteration where the corner screw heads were on the inside of the puzzle instead of the outside, so the material needed to be cut out to leave space for them.