Bien-Air are a Swiss company making dental equipment, especially electric dental drills.  In the late 90s they were entering the implant market which needed very precise control of drill speed and torque. Their existing control systems were not precise enough. I desiged a digital speed readout with better than 1% accuracy and an air operated controller that would limit speed and torque to preset values according to the size of the drill, broach or tap.

I made many hundreds of them over the next few years until the next generation of Bien_Air's electronics control system evolved.

I also made speed and torque controllers and speed readouts for Tridac, another dental supply company