Hobby servo motors are the little wonders that make radio-control boats, airplanes, cars, hovercrafts, helicopters, submarines and robots work. And they are excellent devices for hacking.
Hobby servo motors each contain a little motor, which (through a set of gears) turns the output shaft, which is connected to a potentiometer, which provides position feedback to the controller chip inside the servo, which commands the motor to move until the output shaft reaches the desired position.
We’ve seen all kinds of crazy and wonderful servo modding– from the standard continuous rotation mod to the simple electronic speed controller, to full-on (servo) brain transplants.
Some time ago, I wrote up an article an article in Make Magazine, about how to modify a hobby servo motor to precisely control a one-ton scissor jack. The resulting sub-$100, one-ton linear servo motor can be used for any number of CNC and robotics projects. (For our own use, this was the Z-axis lift motor of the CandyFab 4000.)
We are now pleased to report that this project has just been released to the public over at Make Projects, where they have released a step-by-step version of the magazine article. (So go take a look!) One note: be sure to download the two PDF documents listed under “Files” — you’ll need those diagrams to follow along with the project.
The Hitec 300 series maintains voltage on both motor outputs at rest. That may lead to heating in your transistors as they’re always somewhat on. To avoid that and to gain the advantage of programmable endpoints and deadband using a Hitec programmer use a 5485 digital servo in place of the 300 series pictured.