3D Printed CO2 Car - Part One Design

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This is a project designing and building a 3D printed CO2 car. The car can be mostly printed with the only requirement for assembly being to purchase small steel rods that act as axles. This project is great way to introduce several skills that can easily be turned into lessons. I will be breaking this thing into 3 parts, each containing a separate lesson. The lessons will touch on skills like physics, math, spacial reasoning and design. My target population is 4th and 5th graders but this can easily be adopted for higher grades. I found that getting my students excited about this project was simple. I taught them the basics of Tinkercad. Then I had them start with a template of a CO2 car and let them make it their own. The initial requirement is to go through the 'Basics" tutorial on Tinkercad.com at the very least. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator (5th Generation) Rafts: Yes Supports: Yes Resolution: .3 Infill: 10% Notes: The basic template for a car and wheels takes about 4 hours to print. Post-Printing Final Assembly Assembling the car is simple using the steel axle rods. The only difficulty I had was inserting the eyelets on the bottom of the car for the fishing line to go through. I would have preferred to incorporate this into the design some how. Some times you will need to drill out the axle holes on the car as they may print out smaller than needed. The axles will usually need some spacers between the wheel and the body of the car. I've included an .stl file to print some out. The axle is longer by design to leave room for redesigning the wheel. In the past my students have made their wheels thicker with spokes so they can increase footprint while reducing weight. How I Designed This Designing the Project The design for this lesson came from watching a youtube video on a middle school teacher who was using a 3D printer to print wheel designs for his students' CO2 dragsters. I have several hundred students so I knew buying all the car kits wasn't going to work also we don't have a wood shop so they wouldn't be able to design their wood blank. Then I realized we could 3D print the body of the car too. Overview and Background This project is great way to introduce several skills that can easily be turned into lessons. I will be breaking this thing into 3 parts, each containing a separate lesson. Each lesson will be great on it's own but can be combined to teach a multitude of concepts over a longer period of time much like a thematic unit. NYSED MST learning Standard Standard 1: Analysis, Inquiry, and Design Students will use mathematical analysis, scientific inquiry, and engineering design, as appropriate, to pose questions, seek answers, and develop solutions. Link is here for more STEM based standards.http://www.p12.nysed.gov/ciai/common_core_standards/ Audience This project is intended for 4th and 5th graders but can be easily adopted for higher grades by making the goals a bit more complex and allowing more of a self-guided approach. Lesson Plan and Activity Step 1 Have students spend a decent amount of time using the movable work plane. I found that students can't visualize in 3D so they can't think to turn the work plane around to see the back of an object. In fact rotating objects is difficult too. Step 2 Have students move objects around in reference to the workplane (ie where the object it placed). I found that students don't see the relationship between spinning the object around while moving the view around to facilitate making adjustments. Step 3 Have students us the ruler tool. This is a great way to teach the value of measurement in the design process. I told my students that the air hole has to be exactly one inch off the ground but they couldn't figure out how to do it. The ruler helped. Design Now lets talk about design. The initial part should be a conversation on the basics of a car and what makes it go and how it can be faster. I let my students design their cars with little intrusion to their design process. I only taught them how to combine shapes and merge/group the shapes into a new shape. I also showed them the same process with using shapes to make holes or negative space. Materials Needed -3D Printer -CO2 Launcher -Timer -Axles and screw eyes 3D Printer You'll need a 3D printer that prints at least 6 inches in on direction is a bare minimum since the car is about 5 inches long. If the car is too short it will have trouble going straight. Prices vary greatly so it's up to what you have available at school. CO2 Launcher The launcher is also needed. A few companies sell them and they come in two different types. One type uses CO2 pellet cartridges like some bike pumps and the other is directly connected to a bike pump or air compressor. I have the one that is directly connected to an air compressor. CO2 pellet cartridges can get very expensive when you have lots of students. I suggest you go with the bike pump air compressor option. This one is $100. It's the one I use. I really like it. Easy to repair if it breaks. Most parts can be found at Home Depot. http://itsablast.com/cart/index.php?main_page=product_info&cPath=19&products_id=58 This company has a few designs and it even has a track! Very expensive though. www.kelvin.com Some examples: http://kelvin.com/search.php?search_query=co2+dragster+track Timer Next is the timer. This one is harder to find for a reasonable price. I got mine from www.pitsco.com but www.kelvin.com have some too. It was very expensive at almost $500. You do need it since some races are close and the winner can be hard to determine. It also makes lesson on place value, decimals, and time differences impossible without it. This one is less expensive: http://kelvin.com/kelvin-kel-timer-motion-timer/ This is the one I use from www.pitsco.com. It's $399. http://www.pitsco.com/Technology/Dragsters/Tools_and_Equipment/Launching_and_Testing/Dual_Lane_Race_Timer Axels and Screw Eyes There are a few other things to get like axles for the cars. You can use nails but they can wobble a bit more then the ready made axles. http://kelvin.com/search.php?search_query=390361 You'll also need screw eyes for the bottom part of the car that connects to the fishing line. http://kelvin.com/screweye-7-4mm-i-d/ some of these parts can be sourced somewhere else like your local hardware store but that is up to you. I also printed out some washer and spacers for the wheels and axles. Preparation The design process will go a lot smoother if you first go through some of the basics of using Tinkercad.com. This link will help: http://www.tinkercad.com/quests/ I had all of students complete the basics lessons before I even gave them the template for the car. I also experienced some common problems that are worth mentioning. If you're not familiar with Tinkercad I suggest you try it. It's pretty easy to use and all the content is stored in the cloud so your students can edit it from any computer. My references will be to Tinkercad so if you use something else this part may not be relevant.