I've been fiddling with Rubik's cubes for years and after building a cube solver with Lego I wanted to built something more robust and 'professional'.
A while ago I saw a post on Reddit and I really liked the design but unfortunately no other details were given so I decided to build my own version and publish this to help people looking to build something similar.
It's using a NodeMCU, Nema17 stepper motors and DRV8825 drivers + v-profile and various connectors(some of which are 3d printed) for the frame. I designed a custom PCB to make everything nice and tidy.
The v-shape profiles are connected on the outer corners with 90degrees connectors you can buy but for the top/bottom and middle sections, I designed in Tinkercad some connectors you'll have to print. You can find the files also here: https://www.thingiverse.com/thing:5890181
Print 2x 4 way connectors and 4x 2 way connectors. Print 6x axe connectors that you'll later glue to the center pieces of the cube.
2
Building the Frame
Frame
The frame is based on this reddit post a saw a while ago and I really liked(unfortunately no details were provided so I made my own).
Middle: Connect a 7.5cm and a 12.5cm profile with the 2way connector. Repeat 4 times.
Top: Connect 4x 10cm profiles with the 4way connector.
Bottom: Connect 4x 7.5cm profiles with the 4way connector.
Use the metal 90degrees connectors to connect the top bottom and middle.
Motors
Insert the motors into the 3d printed connectors and secure them with the screws.
Connect motors and the axe with the shafts couplings.
Rubik's Cube
Glue the axe's ends to the cube's centers and you'll have to make a few adjustments to get everything fit snuggly.
3
Electronics
Here is a schematic that you can use to connect your development board to the motors and drivers.
As you can see there are quite a few cables and it can get quite messy if you try to use a breadboard.
To solve this I developed a custom PCB to handle all this. Note that the PCB is designed for a NodeMCU v2 quick drop in.
Once you have the PCB, you'll have to solder the capacitors, pins, power connector and switch. The motor drivers and NodeMCU are dropins.
Note that each driver has a level which mentions which face/color of the cube it will connect to. Use these label to orient the cube in the frame and connect the motor cables.