In this introductory activity, students will harvest parts from a discarded printer or other mechanical device that is earmarked for disposal.
STEM students will engineer moving robots, create kinetic art projects, or other electrically powered mechanical devices over the course of the year in your classes. They can readily obtain parts for these projects by harvesting still functioning motors, belts, pulleys, gears and sensors from discarded printers, copiers, vcrs, dvd players, and other machines in class. Even though the printer or other machine is plugged into a 110 V ac outlet, the components run on DC power, typically between 5V and 12V which means they can be harvested and powered with batteries.
Groups will work collaboratively to separate parts based on their function. As students learn the functions of these parts on a macro level by examining them as they disassemble the machines, they will follow up with research and share information on their findings with other groups. Students will discuss the actual functions of these parts in the machine they have, brainstorm ideas on how they can use them for their own projects and organize them for future use. This will be the start of an “Inventor’s Inventory” of parts they will have readily available at no cost for future projects.
3-5 class periods, depending on extension activities
Safe and Appropriate use of Hand Tools
Sorting by Function
Screwdriver Assortment, including small and medium Philips, Flathead
Torx bits (if applicable)
Hex bits (if applicable)
Goggles are necessary since parts can go flying, even if prying does not occur. There are many high tension springs in a printer and they can end up in unexpected places.
Do not have students take apart a device with a CRT (cathode ray tube) screen, like an old style monitor. They contain large capacitors that can give quite a shock even if the machine has been unplugged for some time.
There are sharp edges in any device that is disassembled. Expect the possibility of a few cuts.
Avoid Prying parts if at all possible. Most of the time it is not necessary, look for hidden tabs that can be worked free.
Student may encounter assembly grease and/or ink during this process. They should be made aware of it and how to deal with it in a safe manner.
Before You Start
Discuss and demonstrate proper tool use. You will be amazed at how few students have actually held a hand tool, let alone used it. Demonstrate how to apply pressure and turn the screwdriver in the right direction (lefty lucy, righty tighty). Show students the differences in screw head styles, such as Philips vs flathead., and Torq vs Hex head if present.
Break it Down
If your students do not have any background in mechanical devices, motors or sensors, explain the differences between these system components in a general way. The human body is a great example for this, since everybody has one and is very familiar with it. Break down simple processes like opening a door into component actions. For instance, the brain (controller) must decide it wants to open the door. The sensors (eyes) must locate the door. The motors (legs) then move toward the door. Positional feedback is provided (encoders) so the legs remain balanced. The image from the eyes (optical or other sensor) assists with target distance, and the brain moves the arm toward the door. The hand feels the door handle (touch sensors) and rotates it.
As a quick extension, have the students break into groups. Give each group a simple task, and have them create a flow chart with motion and sensors feedback, then share what they found with the class.
Finally, explain to students with an example how to take apart delicate machines with respect. That means they respect the structural integrity of components, wire routing etc. and make every attempt to keep things intact. There should be very little if any cutting of wires, breaking plastic or the like. Emphasize that the parts they pull today will be much easier to use with a complete set of wires, fittings, and circuit boards.
By this time students are more than ready to begin. As they determine the best way to take apart the machine, watch for prying and jabbing randomly. Encourage them to follow a systematic approach to teardown. Have students manually operate components, turning gears, rolling pulleys and generally making things move. This will help them figure out what these parts do and get a sense of how they might be useful-and if they should be separated now or kept as an assembly.
Continue to circulate around the room and answer questions. Be sure to wear goggles and check for student use. Remove anything obviously dangerous or messy yourself, such as a glass platen or printer cartridges.
The printer with parts ready to be harvested.
Have students keep wires intact if possible.
Some devices like this printer have an LCD monitor to harvest.
Other components might include a wifi radio such as this.
Together these gears make for a complete power transmission unit for study and use.
Hiding under a secret panel in the scanner section of this printer/copier is a motor with a worm gear with lots of possibilities.
Here is a motor with a positional sensor (encoder) attached. There are lots of future projects with a need for motors such as these.
Here is a method of transferring circular motion into linear motion, using pulleys, belts and a linear rail.
Gears and shafts allow for attachment of parts from motors to moving components.
When students have finished removing and separating components, they should be placed in labeled containers. Containers might be anything from shoe boxes to tackle boxes. The labels may be based on type or component, such as motors, sensors, belts, pulleys or function, such as linear motion, motor control, etc.
Students should be assigned a summary activity describing the parts they harvested and their function. Some will be unknown and will require research. If you have the capability, each group should produce a short video with images cataloging the location of parts, an explanation of the way things work, and safety practices when harvesting from discarded electronics. In addition, students should share ideas on how they would repurpose the parts they obtained for their own projects.