We’ve had a love affair with the Monoprice Select Mini since it came out. The cheap printer has its flaws, though. One of them is that the controller is a bit opaque. On the one hand, it is impressive that it is a 32-bit board with an LCD. On the other hand, we have no way to modify it easily other than loading the ready-built binaries. Want to add bed leveling? Multiple fans? A second extruder and mixing head? Good luck, since the board doesn’t support any of those things. [mfink70] decided the controller had to go, so he upgraded his Mini with a Smoothie board.
On the plus side, the Smoothie board is also a 32-bit board with plenty of power and expansion capability. On the downside, it costs about half as much as the printer does. Just replacing the board was only part of the battle. [mfink70] had to worry about the steppers, the end stops, and a few other odds and ends.