Although jet engines are theoretically quite simple devices, in reality they tread a fine line between working as intended and vaporizing into a cloud of lethal shrapnel. The main reason for this is the high rotational speed of the rotors, with any imbalance due to poor manufacturing or damage leading to undesirable outcomes. It’s for this reason that [AlfMart CNC Garage] on YouTube decided to spend some quality time building a balancer for his DIY RC turbine project and making sure it can prevent such a disaster scenario.

In the previous part of the series the turbine disc was machined out of inconel alloy, as the part will be subjected to significant heat as well when operating. To make sure that the disc is perfectly balanced, a dynamic balancing machine is required. The design that was settled on after a few failed attempts uses an ADXL335 accelerometer and Hall sensor hooked up to an ESP32, which is said to measure imbalance down to ~1 mg at 4,000 RPM.

A big part of the dynamic balancing machine is the isolation of external vibrations using a bearing-supported free-floating structure. With that taken care of, this made measuring the vibrations caused by an imbalanced rotor much easier to distinguish. The ESP32 is here basically just to read out the sensors and output the waveforms to a connected PC via serial, with the real work being a slow and methodical data interpretation and balancing by hand.