Modifying a servo for continuous rotation
posted Jul 14th 2008 6:15pm by Benjamin Eckelfiled under: robots hacks

[robomaniac] shows us how to modify a standard servo to allow continuous rotation. This is a classic robotics hack and has been around for a while, but we really like the way he put this together. Although you may need some soldering and desoldering tools to open the servo up, the hack is a physical one. All you really need to do is cut off a plastic tab on one of the gears. If you want to see an example of a bot you can build with one of these CR servos, he just posted this one motor walker.

Putting the bad English aside, I wouldn’t go about modifying a servo for continuous motion like that. You lose one kind of nifty feature by removing the whole controlling logic, which is the ability to drive it in two directions easily. Depending on the servo, you might also lose ability to drive it faster or slower in two directions.
What I would do, is to remove the linkage between the gears and the potentiometer that senses where the gears are. Then remove the tab from the gears that is explained in the Instructables.
Then set the potentiometer to halfway. When you command the servo to go to its maximum, it spins fast forwards (but never reaches the goal). Make it just a little bit over the halfway and it’ll crawl forward. The same applies for reverse motion as well.
Posted at 7:04 pm on Jul 14th, 2008 by Entropia