Project: Pinewood Derby

thingiverse

Thousands of young scouts around the world create their own derby cars, with many racing them every year in the United States. I designed a car to be printed that would have taken much longer to make out of wood and been quite difficult. This project encourages out-of-the-box thinking to create your own unique derby racer. Print Settings: Printer: HK Fabrikator Rafts: No Supports: Yes Resolution: 0.2mm Infill: 100% Notes: I printed with a wood filament from China that gave a pretty amazing wood grain look to the final print. The first print I made was so awesome, I never tried printing it in another material. How I Designed This: I started out with a standard pinewood derby kit which has a block of wood and some general car specifications: overall width 2-3/4", overall length 7", width between wheels 1-3/4", bottom clearance to track 3/8". Many race runners provide an extensive list of additional rules to comply with. I took measurements on the block. Notes on my derby design from my engineering notebook: I loaded up Fusion 360 and sketched up the block. Then, I marked out where my wheels would go and got a rough idea of how much material I would need to hold my axle nails. I then switched to a view where I drew a half profile of the cone, then rotated it around a central axis to generate the cone. Finally, I had to model up the connections between the axle holders and the cone. Then on to printing. A few hours into the 13-hour print. Overview and Background: Thousands of young scouts build derby cars and race them every year. 3D printing a car within the rules brings about different ideas that are not easily made with traditional woodworking techniques. This project is to demonstrate at least one complex shape that is easier to construct with 3D printing as compared with traditional wood working. The derby construction and racing itself is filled with all sorts of STEM-related topics that work together to get you the fastest car down the track. Objectives: Learn how 3D printing enables designs that were previously hard to obtain. Learn the mechanics involved in racing a derby car. Race a car you designed and printed! Standards: MP.4 - Model with mathematics. (HS-ETS1-1), (HS-ETS1-2), (HS-ETS1-3), (HS-ETS1-4) RST.11-12.9 - Synthesize information from a range of sources (e.g., texts, experiments, simulations) into a coherent understanding of a process, phenomenon, or concept, resolving conflicting information when possible. Lesson Plan and Activity: Step 1 - Background Knowledge: Discuss the physics of a derby car. Discuss friction. Discuss how 3D printing unlocks new and imaginative designs that were previously impossible to make. Step 2 - Practical Testing: Assemble cars Setup a track Run the cars on the track Step 3 - Calculations: Average the heats to determine the car with the fastest speed Calculate the fastest car Calculate the fastest lane Calculate the speed If you printed with different properties, aggregate the data and have students plot it out looking for results from the incremental changes. Step 4 - Review: Compare and contrast the race results with the designs Discuss why we got the results we got Discuss how students think they could use the results to design a different car. Materials Needed: The following materials and items can be helpful with this project: Pinewood derby kit - sold at scout shops and craft stores Calipers, rule, or tape to measure or layout with Multi-lane track to race on Weights - washers, sinkers, pipe soldering lead, tungsten, etc. Scale Graphite Sandpaper Paint Calipers, rule, or tape to measure the broken cross section Protection gear - eye protection!! and any other gear that might be a good idea. Rubric and Assessment: What is friction? How does potential energy convert into kinetic energy? How fast did the cars go? What was the most influential design parameter on final outcome? References: http://pinewoodphysics.com/index.html https://www.wired.com/2010/12/pinewood-derby-physics/ See Mark Rober's Youtube video below - science of pinewood derby A quick video of the printed funnel car running. Pack 146's 2016 Derby Race Mark Rober's Video on Pinewood Derby Cars