Our assembly process for this can differ for how you want to make your circuit. The enclosure can be different, and you might even want to try other servos from the Adafruit store. The calibration, though, is very important and you'll want to "dial in" your servo to make sure it's going to display perfectly.

Dialing in your Servo

First, we should move our servo to its center location. Download and run this small Arduino code. It'll move the servo to it's center location:

 *  Servo Centering Script

#include <Servo.h>

Servo myservo;  

void setup() {

void loop() {
  // change this depending on where you're centering

You should see your servo horn move to the center. Take the horn off your servo (if you screwed it on, you'll have to unscrew it), and mark the tip of it with a marker. This will be your indicator:

Reattach the horn onto your servo (which should now be in the 90 degrees position) and you're ready to roll!

Assembling an enclosure 

Let's build an enclosure so that you can use this on your desk at work, or somewhere in a room. The ever so talented Dano Wall whipped up a printable, cut-out, design which fits on top of the box that your metroX kit came in. It's a dual-dial design that works both with Fahrenheit and Celsius . You can download the design below (it's open-source and totally modifiable):

Test-fit the printed dial against your MetroX box, then cut it out along the outer black line

Tape the four corners (we only taped two in the gif below) of the paper to the inside of the box. Use transparent tape if you can, it'll look much cleaner:

Use a box-cutter or the edge of a pair of scissors to cut out the servo cut-out (the rectangle) on your printed design. It might take a few cuts to get through the box completely:

Clean up any residual cardboard from the hole you cut. Tape the servo in the rectangular hole, facing outward:

Finally, you'll need a pointing device. We used the inside of a disposable pen since they're inexpensive, and a lot of people have them lying around:

Great job! Close up the box and get ready to program:

This guide was first published on Aug 18, 2017. It was last updated on Jul 12, 2024.

This page (Assembly) was last updated on Mar 08, 2024.

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