Geared Motor Servo Conversion




Introduction: Geared Motor Servo Conversion


This is a quick little project i did one night after work!

I was itching to solder something, so here it is! My cure for boredom! 

You will need the following:

1 x Servo
1 x Screwdriver
1 x Soldering iron
1 x Wire snippers
1 x X-acto knife
1 x Connectors of your choice 


Step 1: Take It Apart!


Take your servo apart!

Remove the four screws at the bottom. Get rid of the servo wires (snip or de-solder, your choice)

Do the same with the 3 wires connecting to the motor.

Step 2: Gut It

Now take it apart completely, all the gears should pop out pretty easily, remove the motor and the small circuit board connected to the potentiometer.

If you want to keep the small circuit board & POT, go for it, but otherwise, throw 'em out, we won't be putting them back in the motor!

The motor should be attached by two small screws. DONT LOSE THEM!

Step 3: Modify the Gears


A servo is only made to rotate a certain degree range, we have to change that.

Put the big gear that attaches to the servo horn in a clamp or vice.

Take your x-acto knife and remove the stop tab.

In this particular servo two of the teeth of the gear are filled in, simply cut the teeth out with the x-acto knife!

Step 4: Reconstruct!


You're almost done!

Now solder your own wires or connectors to the small motor & screw it back in place!

Your ready to put it all back together, simply put your modified gears back as they were.

Put the four screws back in the case & run your wires out where the old ones were!

Step 5: You're Done!

You've done it!

Now you can use this anywhere you need!, without a servo tester or tx/rx system! In my opinion it has a great ratio between power and speed (of course this may vary between servo models) but overall this thing rocks!

Hope you enjoyed my Instructable! 

- Max

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    7 years ago on Introduction

    i thought this insructable was about making a gear motor into a servo


    9 years ago on Introduction

    Or you can leave the electronics in, but cut the arm of the potentiometer.
    Then you can control it like you would a normal servo, and use it as a motor without needing to make an H-bridge.


    Reply 9 years ago on Introduction

    I have to agree with sdfgeoff.. You needn't go as far as massive rework, when the majority of the work is already built-in.. Just a matter of minor modification to the main drive gear to remove any kind of 'stop' tab, and removing the potentiometer, and replacing it with a pair of 2.2K resistors in a "W" (or "M ") wiring, connecting the two resistors in series, connecting the free ends to the outer-connections for the pot, and the center of the two, to the wiper connection on the servo board. Then, simply sending a PWM train signal to the Signal pin of the servo, and simply supplying 4.5-6V to the servo power pins. Unless you really want to go as far as the H-Bridge, and have direct control of the servo motor.. Just seems a lot of extra effort to rebuild the mouse-trap, so to speak.


    Reply 9 years ago on Introduction

    It just depends what use you have in mind.
    Some mirocontrollers may not be able to output a pulse necessary to drive the servo without stopping all other processing (the old basic stamps had this problem I think), and so it is then better to use an H-bridge.


    Reply 9 years ago on Introduction

    That is a great suggestion!

    In this instance i just wanted it to be as bare bones as i could make it, and its less work to just pull it out!

    Thanks for the reply