This jig seems like a better option than eye-balling it ¯\_(ツ)_/¯ Nicholas Ryan, Aaron Dubiansky on Hackster.io:
The potentiometer is programmed with two functional buttons and a OLED readout. A button located on the particle board managing the sensor operation will run a code calculating maximum deviation of the wheel as its spun over a 10 second period. This data will be posted to ThingSpeak as a graph to track ones progress is improving the true of the wheel. Another button located on the particle board managing the OLED can be pressed once the wheel is mounted to zero the sensor at the point where the wheel deviates farthest from the sensor (ensuring the wheel always contacts the sensor). As one spins the wheel, the sensor will update every second and provide a readout.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.