Basic Homemade Actuator

Last night I tried an experiment to create a simple actuator to see how easy they are to build. These are very useful in mini- remote controlled airplanes because they can be built much lighter than servos. I started by taking apart the fan motor from a microwave. The motor had a coil of magnet wire on the bottom that was easily removed. Old motors are a great source for free magnet wire which is the most important part of an actuator.



In the above picture you can see the gap that the coil was removed from. The coil was very easy to remove. I was able to simply tap it out with a tap and a hammer. Below you can see the resulting coil. This coild has a lot of magnet wire on it and it is as easy to pull it off of this spool as it would be if new wire was purchased on a spool.



Next a took apart an old pen to use as a tube to wrap my new coil onto. I used blue painters tape to tape the two end leads down so that it wouldn't come apart. I wraped many turns of wire onto this tube. To make it go faster, I chucked the tube in my cordless drill and ran the drill with one hand, and guided the wire with the other. This went surprisingly fast and easy. The entire coil can be wound in a couple minutes.




When the coil was finished I mounted it on a board to make experimentation a little easier. This coil is much longer than the type you would use for most actuators on RC applications. It is a couple of inches long and when I quit winding I measured about 25 ohms of resistance. I believe most RC airplane actuators are only about 16 ohms, so I have much more wire on here than would be needed for one of those.



I soldered the leads from the coil to some thicker solid wire that is easier to work with. I then hooked up a 9 volt battery with some wires that could be hooked up to try it out.




I used a nail as the moving peice. When turned on the coil's magnetic field attracts the nail and pulls it inside. A stronger actuator would use a permenent magnet. Below is a movie of the actuator in action.



This project was very simple and took only about an hour to do. The next thing I would like to try is making a more powerful and lighter version that could possibly be used for controlling a mini rc airplane. The first change would be to use a small, rare earth magnet in place of the nail. I would also make the coil only an 1/8 of an inch wide but with many more layers of turns on it. This should concentrate the magnetic field and make it more powerful in the one spot.

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