Introduction: K'nex Flywheel Ball Launcher (by Austron) Instructions

About: I'm french, I live in a house, I love build stuffs with K'nex and Arduino, I have a YouTube chanel, and i enoy building some devices for Halloween

Well, seems like i was too lazy to do those instructions sooner.

So, 2 years ago i reproduced the Austron's flywheel ball launcher by watching this video and i did photos for instructions. So here it is :-)

Step 1: Pieces Count

I will probably do it later (maybe never), if someone want to do it, feel free to post it in the comment section

Step 2: The Frame

Step 3: The Differentials

What the hell is a differential ???

this animation represent perfectly how the differential of this machine work:

the green gear in the video correspond to the big yellow gear in our differential.

This is how it's working:

when the motor start moving first it rewind the spring motors and the yellow gear don't move

Then, when the spring torque compensates the motor torque the spring motor shaft is maintained gradually in a balanced position and the movement is gradually transmited to the yellow gear

The torque provided by the motor and the spring motors is transmitted to the yellow gear wich cause the springs to unload a bit, but because the spring motors torque became lower than the motor torque, a bit of the movement generated by the motor will rewind the springs to balance them again while the main part of the movement is still transmitted to the yellow gear. Then again the spring motors will unload a bit and supply torque to the yellow gear.

But why do we made this complex things ?

It's simple (or not): we need to provide an high speed rotation to the last shaft of the mechanism (not build yet), however in any mechanism when a gear multiplier is used, the torque at the end of the multiplier is lower than the torque at the begining. But the k'nex motors torque is pretty low, so to solve this, first we use a flywheel to keep a motion inertia in the mechanism (the mechanism won't get stuck suddenly when it will launch a ball, and the lock clips won't get disconnected thanks to that) and then our differential take action, when the machine launch a ball, the mechanism is suddenly slow down, but the 2 motors are still spining at the same speed than before. So the exessive motor torque is transmitted to the spring motors thanks to the differential wich will rewind them even more. And thanks to the biggest pressure in the springs than before, the initial high speed is gradually reestablished and the spring torque came also gradually back to normal

Step 4: Assemble

Watch out ! 12 volts motors may not spin in the same direction depending where you buy them !

If the mechanism don't work connect the motor in the opposite way.

Step 5: The Input Shaft

Step 6: The Flywheel

pro tip: don't put your finger nearby when it spin x)

Step 7: The Gear Box

Step 8: The Launch Wheel

Step 9: The Ball Track

Boom it's done !