What gearboxes go well with redlines or 775 pro motors from the KOP this year for shooters. We need lots of speed so we need an induction gearbox.
Not sure what you mean by induction gearbox, but we’ve successfully tested planetary gearboxes with 775 motors for shooting. Our longest-distance prototype yet uses 2 horizontal wheels, each driven by an redline attached to a 57 sport with a 4:1 ratio.
It’s totally a repurposed power cube claw.
I mean a gearbox that increases in speed. I love it they’re just spherical power cubes lol
The free speed, or unloaded speed of the 775 is quite high, in the ballpark of 18k RPM. I think you’ll find that this is too much speed/too little torque for shooting the ball. CIMs or MiniCIMS would be a better speed if you’re going direct driven. “Overdrive” gearbox is the term for a gearbox with an output speed higher than the input motor.
I believe OP means “reduction”, since the output shaft should spin slower than the input motor.
For RedLine or 775pro motors, the Coke and Pepsi of the game are the VEXpro VersaPlanetary and AndyMark 57 Sport. VPs will give you more ability to swap around ratios as you see fit, while the Sports tend to have a little higher load rating (not as important in a shooter situation, but important elsewhere) and tend to be cheaper when compared apples-to-apples to a VP configured the same way.
What RPM do you want at the wheel? I think you’ll find that somewhere around 5000 rpm, plus or minus a bit, would be about right. So you need somewhere around 3:1 speed reduction from the motor to the wheel.
For testing a prototype we have been using a BAG motor with a 12:1 reduction with a 6 in wheel on the shaft. That wheel contacts a 2in wheel connected to the drive shaft. Not sure what rpm that is but it works well.
The free speed of the BAG is ~13k RPM, so you’re spinning the shaft at about 1000 RPM. If you have something that works, that’s great. I think you would see a performance increase with 775/redline motors. The other advantage would be the option to spin the larger motors at a lower voltage, giving you head space to recover lost speed from shooting a ball, and using less power overall.
Thanks for your help
Just to be clear, are you saying that the output shaft of your 12:1 gearbox has a 6" wheel on it that is then transferring power to a 2" wheel by tangential contact? If so, then that wheel-to-wheel contact is actually an additional ratio you need to account for when designing your final shooter. With a 6" wheel driving a 2" wheel, that’s a 3:1 overdrive. Combining that with a 12:1 reduction from the BAG motor gives a total of 4:1 reduction needed. You can get that both from a VersaPlanetary and a 57 Sport, as well as through a custom GT2 belt reduction.
That’s a pretty nifty looking prototype
I’d use a belt reduction since they’re light, allow for short distance power transmission that can allow for better packaging, and they can be easier to service.