Continuous Rotation 4.3g Servo

The object of this is to detail how to turn a small 4.3g into a continuous servo

Step 1:

First step is to open up the servo and carefully open the gear pack. There will be one large one that is the output shaft and remove this. At the bottom you will see a boss that fits inside the potentiometer of the servo.

Step 2:

With a pair of cutters, just snip off this little piece at the end.

Step 3:

Now place the gears back and fix the top of the servo temporarily with some tape. Open up the bottom and move the servo control board out of the way. You want to connect the servo up now to drive it to the mid point position. You can do this with a servo tester, a radio control or with an arduino sketch. I've attached mine at the end.

Step 4:

With the servo at mid-point adjust the pot until the servo stops moving. Then you can see that by increasing the servo command a little each way the servo will go into continuous drive mode in each direction. When you are happy that you have found the dead point, add a drip of super glue to the pot so that it doesnt move.

Step 5:

Re-assemble and you now have a servo that will travel continuous in each direction.

Step 6: Arduino Program That Takes Text Input to Output a Servo Position

Use this to work out the midpoints and the max and min, just connect the servo to pin 2 of the arduino and the positive of the servo to VCC and the Gnd to Gnd. You can then type in various positions for the servo to move to so that you can work out the different speeds and find where the dead point is.

Comments

[johnip4]

I've never tried it with the mini servos, but I swapped the motor leads on a regular sized one so that it rotates in the opposite direction. That way you can drive both sides of a wheeled robot without using different timings for each servo.

[Ajaxjones]

nice idea, will try that in another tracked robot I have. For this the servos are opposed driving the front and rear on each side so they are both aligned.