I have been on a stepper motor odyssey lately. It all started with the Z-Axis stepper being too weak – or at least I thought so. It was simply unable to lift eough weight and ordered another one, but it had the same issue. I was puzzled, but finally found out that it did not get enough power from the Rambo-board. You can adjust that by changing values in code and voilà, the motor got much healthier. I decided to allow all motors to consume a little more power, but apparently that led to overheating motor drivers. You know that your driver is overheating when the motor starts skipping.
I decided to overcome the issue by adding a fan to the control board’s enclosure. It’s a PWM-controlled fan, so I had to give it some sort of control circuitry. I simply want to control the speed with a rotary knob, so adding a timer IC and stuff would have been the “right” way to approach this, but I still have some low-memory Arduino Nanos lying around that I accidentially ordered because I did not know that there are different versions. For controlling fan speeds they are perfectly fine though. I was toying with the idea of throwing a temperature-sensor in there to adjust, the speed based on the driver temperature, but then again why overcomplicate things.
In the end I drilled a lot of holes into the formerly closed front surface of the blue control board housing and mounted the fan together with a 3D-printed fan-cover. Temperature-wise the MPCNC seems to be happy now