H-F Lathe 34706 Speed Sensor Optical Interrupt Disc 3a

This object was made in Tinkercad. Edit it online https://www.tinkercad.com/things/d6gxn6prP8k. The slots on the top surface are for nuts that are used with machine screws to secure the disc to the shaft of the lathe. Used with an optical interrupter module, it can be used to measure the rotational speed of the lathe. The 60 holes around the perimeter make it so that a frequency counter can read directly in RPM, since 60 pulses per revolution (PPR) / 60 seconds = 1 RPM. Optical interrupters are available on Amazon, at DigiKey, and other places.