Servo Test Dial

Look, a servo dial! The tool allows you to verify:

  • The operation of a servo
  • Quick reference the sweep angle, checking repeatability
  • Setting up trims and subtrim
  • Confirm servo’s travel adjustment
  • Check zero deadband similar to this

You need the following to start:

  • Computer with graphics illustration software (i.e. Inkscape)
  • Laser or inkjet printer to print dial label
  • Pair of scissor to cut dial
  • Junk CD/DVD you no longer use
  • Glue to stick cutout dial onto CD
  • Adapter ring
  • Spare servo horn
  • Thin plastic sheet, cut out for hand
  • Servo, radio, receiver and battery
  • A servo holder

Secure the servo on a vise

The adapter ring

The adapter ring is a small aluminum piece which we machined. By measuring the diameter of the circular part of servo, we machine the ring a tad undersized so we can press fit the ring by hand. The outside diameter of the ring aligns with the CD center hole, which is 15mm diameter.


With the dial printed, trimmed and clued onto the CD, we placed the CD onto the ring

Now trim the thin plastic sheet as pointer and attach it onto the servo horn, install servo horn onto servo, turn disc to set pointer pointing to 0 degree.

All set and ready for testing.


Team BTF.

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