360 Degree Servo Mod

The other day, we saw Peter messing around with some servo toys. These were unique in the fact the servos were spinning all the way around continuously.

Servos normally don't do this but today Peter shows us how to free up the limits on your servos!

The servos we use day-to-day are the standard 9 gram servos (which are plastic gear) and the EMAX ES3154 (which are metal gear)

The principals used will apply to all types of servos, but the layout of the components may look a little different depending on your brand.  

The first step is to open up the servo.

Once you have it open, DO NOT start ripping gears out right away. Take a good look at the layout, or better yet, take a picture. The gears will need to go back in just they way they are when we are all finished. 

Once you have a good idea of how the gears sit, remove all the gears and any pins holding them in. 

The idea behind this is pretty simple. Inside of the servo is a potentiometer. This is the device that limits how far the motor spins in one directon or the other. All we are going to do is trick the servo so the potentiometer never recieves any feedback information, therefore, it won't know where to stop and will spin indefinitely.  

Next, you'll want to center the potentiometer. Hook up the servo to a centerer or center the trims on your radio if it's bound. 

Once you hook up the power, you'll hear the motor make a high pitched noise. This means it's trying to move the motor to move the gears which move the potentiometer. Move the potentiometer left or right (slowly!) until the motor stopps humming. This means the potentiometer is  "centered" so it stops moving the motor which is exactly what we want!

Now that the potentiometer is in the correct position, lock it down with some super glue, or use thin/medium CA. 

The potentiometer is hidden on the EMAX servos a bit. You'll have to look at the bottom under the wires. Just like the 9-gram, stick a screwdriver in the slot and rotate left or right until the motor stops humming. Glue it down so it no longer moves. 

On the 9-gram, find the gear that normally rides on the potentiometer rod. You'll notice a little plastic tooth that will lock the gear down if it moves to far one direction or the other. Take a razor and cut the tooth off (or sand it down) 

Find yourself a drill bit that slightly larger than the potentiometer rod. 

The gear that provides the feedback to the potentiometer is usually friction fit. If you take away that friction, the gear will spin freely on the rod. This is how we negate any information going to the potentiometer. It's now glued down and the gear that usually talks to it will do it's best impression of the teacup ride at Disney. 

For the metal gears the rod is not on the servo body, but the gear itself. The exact same idea applies, just remove the rod that would talk to the potentiometer! Be careful of sparks and debris when cutting metal! Wear saftey glasses and don't hold it in your hands. Peter is reckless. Don't be like Peter. 

All that's left to do now is reassemble the gears just how they were and screw the housing back together. 

These can be used for literally anything you can come up with. Peter build a cool camera phone slider, a winch system, and a little RC rover all with these moded servos. What kind of projects can you come up with. Maybe a cool 360° FPV rig?

Whatever you come up with, take some pictures, shoot a video, and make an article! Show the community just how awesome you are!