Rpm counter for root2cnc

thingiverse

The counter leverages an optical sensor consisting of a transmitter and photodiode, accompanied by a small piece of reflective tape fixed to the spindle's fan. A circuit with an opamp connects the photodiode directly to an arduino mini, measuring the signal period and transmitting the rounds per minute to a 0.96'' OLED display (priced at approximately two euros on aliexpress). The box attaches magnetically to the spindle via two small magnets in each arm. Two versions of the support exist, featuring distinct hole sizes to accommodate different magnets. Those interested can acquire schematics and source code from me. Although designed for root2cnc, I believe this counter could be used on other cnc machines as well. The support's curvature is suitable for a 52mm spindle but can easily be adapted to fit various spindles.