Note: The motor clip was remixed from someone else's design that just had a hole to screw it in; I added the base so it could be glued and made it slightly smaller to fit my motors more tightly. I cannot find the original! If you think you know whose it was remixed from please let me know and I will give credit!
This was created for summer camp engineering challenge for 5th-7th graders. The camp was space themed so this activity was to design a 'rover' which would then be tested on different surfaces and with different loads. The day was engineering themed so they got a lesson in the engineering process to introduce the day.
Then we discussed how circuits worked (which they had good background of) and practiced with Snap Circuits then were given the challenge to create their own rover using any of the given parts (within limits of a maximum amount of each printed part). I purchased motors and battery packs with lead wires attached so all they had to do was twist wires together and tape them with electrical tape; I didn't want to have to use solder but this could be an option for a more advanced class. I had considered using mini solar panels as well but decided against them due to time and budget constraints. Instead, we discussed how reusable batteries could be used and a solar panel used to charge them. The project took the students much longer than expected, maybe 3 hours in total over 2 days and they could have kept going, but they were very engaged the entire time and did a great job troubleshooting and reworking their designs.
I created a model ahead of time which I showed them first and discussed some of this things to consider while designing and creating their rover:
-Tape and test the part in a certain spot before marking and gluing it on.
-Be careful will lead wire attachments.
-Think about weight of car and load.
-Think about the direction your motor is rotating.
-Think about where and how the force of the motor is being applied.
-Make sure battery pack is attached with switch accessible and top able to open to replace batteries; place top up and switch down hanging off an edge to access switch)
Each student engineered their own rover so I made sure to have enough materials to give the students choices.
Material options were:
-Large Pulley (max 1 per student)
-Small Pulley (max 1 per student)
-Motor Pulley (max 1 per student)
-Large Wheels (max 2 per student)
-Small Wheels (max 4 per student)
-Motor Clip (max 1 per student)
-dc 130 motor (purchased from amazon with lead wires attached)
-Battery pack with switch (purchased from amazon with lead wires attached)
-2mm x 150mm axles (purchased from amazon)
-Straws (these were used to hold the axles)
-Popsicle Sticks of various sizes
-Various size rubber bands
-Balloons (could cut a cross section and put around wheels for traction- no one really caught onto this as I didn't tell them their use so they instead used them to decorate and play with... until they got taken away.)
-Old CDs (could glue to wheels to make larger wheels)
Their designs ended up reflecting my model quite a bit, if I had more time or older students for the project I would not have made a model but rather had them try their own designs first. Another adaptation could be only printing smaller wheels and having them adapt them with cardboard, CDs, et c to make them the size of their choosing.
Pulleys will need supports, wheels and motor clips do not. Wheels could be printed at 12.5% infill.