Kumiki cube

This wooden original cube is probably designed by Tsunetaro Yamanaka (born 1874).

I got it from my grandfather in the 1970s.

More updates may come, let me know what you think of v2.1.

Update 11 March 2025

I printed v2.1 on a Prusa MK4 at 0.05mm and find the pieces better fitting. A single cube does take over 22 hours to print.

The only issue is the overhang (photo between the two blue arrows) on the biggest piece, this may need some scraping or cleaning (0.05 is not much).

Update 10 March 2025

Currently printing, if it works then v2.1 is available tonight.

Update 8 March 2025

I am printing loads of these and still find some issues!

For example the last piece being really hard to insert/remove or it being too loose so it falls out. This could be caused by the orientation in which it is 3D-printed on my MK4.

So better wait with downloads until v2.1 or v3.0.

Version two is much better!!

Instead of drawing all the pieces in FreeCAD, and ending up with an uneven cube when assembled, I decided to program all the pieces in Python. The result is a smooth cube, no extruding pieces but smooth sides. (The grey one in the first picture.)

3D-printing

I used PLA and printed v2.1 on MK4 without Input Shaper.

The big pieces have an overhang, but it prints fine without supports. They may need a bit of scraping or cleaning on the overhang (see the picture above).

Assembly

Here is a video on how to assemble it.

Though it is not that hard, so try it yourself for the most fun!

Design

I have several wooden Kumiki cubes, with slight variations in the sizes of the parts. See this for example:

This design resembles my oldest Kumiki cube the most. But it is easy to adjust in the FreeCAD source file.

More information on my design decisions will come later.

License

The design is well over 120 years old, so probably no copyright.

I included the FreeCAD source, consider it Public Domain.

Nice people will point to this page https://www.printables.com/model/1213988-kumiki-cube