Our team is looking for gearboxes for the large, black motors that come with the KOP. I believe they are CIM motors? Anyway, we want a 1:1 gearbox for them, and were wondering if there are any avaliable just for purchase. The CIM-ple transmissions are like 4.79:1, which is all we have.
Their is no such thing as a one to one gear box, I think. You could direct drive what every you want assuming a shooter. The easiest way would probably be a coupling that fits over your cim shaft and your other drive shaft. Or you could run a belt from the cim to your shaft with the same number of teeth.
The motors are indeed the CIMs. However, I REALLY question why you want a 1:1 gearbox. I don’t know of a single gearbox like that (unless you count the keyed output shaft), but unless you’re running them under no load, they might have a heck of a time accelerating to top speed.
Why are you looking for a 1:1 gearbox? If you just want a usable output shaft, what you need is a shaft coupler. If you’re just trying to face mount the motor to something, then you can just drill those holes yourself. If you’re trying to mount the CIM in one place and power something far away at a 1:1 ratio, chain and sprockets or belt and pulleys are what you want.
I would caution you maybe to use another or a combination of motors to power the shooter and leave your cims in the drivetrain. Any drivetrain with 2 or even 3 cims worth of power (~ 900 watts), is going to be fairly deficient in a pushing contest, of which there are many in FIRST. If you do use the cim, there is no reason to use a gearbox. The purpose of gearboxes is to change the rotation speed or torque being applied by a motor, and if you are simply looking to transfer power, use chain.
save the sims for your drivetrain, use FPs or 775’s for your shooter. And if you insist on using a CIM to power you shooter, I would advise against using a 1:1 ratio, assuming your using the CIM to power a flywheel. Your wheel will take a while to accelerate to full speed and every time a ball is fired the wheel will take a while to get back up to full speed. I would recommend 1 or 2 banebots or FP’s geared around 3-5:1. And if you insist on using a 1:1 ratio for your shooter just use a shaft coupler, a 1:1 gearbox is completely redundant and just adds extra weight and cost to your robot that you don’t need.
A 1:1 gearbox would basically be two gears of the same tooth count. What about that arrangement precludes acceleration at all? There is inherent friction in any drive setup, which is why adding a gearbox to a CIM motor for no reason might not be the best idea, but it wouldn’t preclude acceleration. Any flywheel from Aim High that directly drove the wheel would have similar performance to a CIM motor off a 1:1 gearbox.
I would recommend 1 or 2 banebots or FP’s geared around 3-5:1.
I agree with the recommendation, but you do realize that the output you’re describing is not that much different than the bare output of the CIM, right?
CIM torque in relation to speed, if there was a large load (say, in drive). As it’s a lighter load, that’s less of an issue. I will note that when 330 ran a big CIM for a shooter in '06, we did apply a small-ish reduction, in two stages (one belt, one 25 chain), and had zero problems.
I have experience running 6" 2008 KOP wheels direct to a cim. in fact, I was the machinist who lathed up the shaft.
3 wheels, no added weights, using a custom shaft machined from 1/2" hex steel (AL= fail) was able to shoot a 2009 orbit ball into a 2009 trailer 10ft away. however, after a few shots the shooter lost a considerable amount of RPMs, so a flywheel prototype was attempted, which took too long to rev up. In the end, code was written to add a extra bit of power for every successive shot in a certain time window at a given power level.
using such a config this year may not even need such code due to the possession limits…
Well, our team is completely new this year and we don’t really have any mentors so we’re trying to figure it out by ourselfs. We’ll try some of what you suggested. Last year, they didn’t use 2 motors on the drivetrain, just one. Interesting.