Microstepping A PCB Motor
Over the last 2 years [Carl Bujega] has made a name for himself with his PCB motor designs. His latest adventure is to turn it into a stepper motor by adding position control with microstepping.
The NEMA stepper motors most of us know are synchronous stepper motors, while [Carl]'s design is a permanent magnet design. It uses four coils on the stator, and two permanent magnets on the rotor/dial. By varying the current through each of the four poles with a stepper driver (microstepping), the position of the rotor should theoretically be controllable with good resolution. Unfortunately, this was easier said than done. He achieved position control, but it kept skipping steps in certain positions.
The motor and controller consist of a single flexible PCB, to reduce the layer spacing and increase the coils’ magnetic field strength. However, this created other problems, since the motor shaft didn't have a solid mounting point, and the PCB flexed as the stator coils were energized. Soldering the controller was also a problem, as the through-hole headers ripped out easily and the PCB bulged while reflowing on a hot plate, in one case even popping off components. [Carl] eventually mounted one of the PCB motors inside a 3D printed frame to rigidly constrain all the motor components, but it still suffered from missed steps. Any suggestions for fixing the problem? Drop them in the comments below.
Like his other PCB motors, the torque is very low, but should be suitable for gauges or clocks. A PCB clock with an integrated motor would be pretty cool to have on the workshop wall.
The TMC2300 stepper driver [Carl] used belongs to the same family of drivers that enable silent stepping for 3D printers. We’ve covered a few of [Carl]'s PCB actuator adventures, from his original design to linear actuators and a flexible POV display.