Marble Coaster Launcher

thingiverse

This Thing is the 3D-printable body of a spring-loaded ball launcher which launches a 1" ball in a marble run or marble coaster. The front of the launcher is designed to securely hold 1/4" (outside diameter) polyethylene tubing which serves as rails for guiding a 1"-diameter marble along the track. The tubing just snaps into place. I use tubing from Lowe's: https://www.lowes.com/pd/EZ-FLO-0-170-in-Inner-Diameter-x-150-ft-Polyethylene-Tubing/1000365053 or https://www.lowes.com/pd/EZ-FLO-0-170-in-Inner-Diameter-x-25-ft-Polyethylene-Tubing/1000180489 Although I imagine any 1" ball will work, the ball I use in my marble coasters is a 1"-diameter solid plastic ball from Pasco Scientific (comes with their physics projectile launcher). They can be bought from Pasco in packs of ten: https://www.pasco.com/products/lab-supplies/other/me-6822 This launcher was designed to use a spring from a "Master Plumber" brand toilet paper roll holder available at True Value hardware store: https://www.truevalue.com/toilet-paper-roller-white-plastic I bend about 10 mm of the wire at one end of the spring so that it sticks out straight, feed it through a small hole in the back of the launcher, then bend it over to secure it. See the photo. The rear cap is totally optional. (I include the cap because it covers that bent piece of wire protruding from the back of the launcher. It will attach to the body of the launcher with three 3/4"-long #6 steel screws (Hillman item # 80018).) The launcher has five spring compression distance settings. Five holes on the top of the launcher allow you insert a pin (or dowel, screwdriver, large nail, etc.) to hold the ball in place until you are ready to launch. Then you just pull the pin and the ball shoots out. I use a steel pin from Lowe's because it has a ring that allows me to tie it to a string so it is not lost: https://www.lowes.com/pd/Hillman-1-3-4-in-Cotterless-Hitch-Pin/3012936 I have posted a separate Thing which includes 3D-printable clips for spacing and securing the poly tubing track rails in the rest of the coaster: https://www.thingiverse.com/thing:5265850 EYE PROTECTION SHOULD BE WORN WHEN USING THIS LAUNCHER! The ball can be moving from about 6 miles per hour to faster than 20 mph depending on the setting. Fellow physics teachers: If you use this launcher with your students I'd love to hear about how your activity went! And I'm always looking for tips for improving this project for my students. My Twitter is @Misterfizzx .