Toughbox vs KOP Toughbox Mini

[Gregor]

Originally Posted by valkyrie2240

I've been looking at the differences between a normal 12.75:1 Toughbox and the KOP 10.71:1 Toughbox Mini for my team's chassis this year. I've been looking through the quick build chassis guide to see if using the Toughbox vs the Toughbox mini would change the assembly at all. I'm specifically looking at how to mount the toughboxes. Would anyone happen to know if we would have to make any changes to the KOP chassis to mount a normal Toughbox instead of the Toughbox mini?

Any particular reason? We have quite a few Toughboxes. They weight a lot, and you can get a decent speed out of the Toughbox Mini.

[nathan_hui]

Probably, since the big toughboxes were originally paired with the old KoP chassis (which is now illegal, I believe). But what do I know? I suspect you could, but do the math (you need to make sure that the output shaft of the toughbox doesn't interfere with the wheels, and that's pretty much it.)

[Jon Stratis]

Your biggest concern is problem spacing with the output shaft... you'll need to make sure you get proper alignment and tension with the belts the KoP drive train has now! It may be a little trial and error, but I think those old Toughbox gearboxes had enough adjustment capability built in to make this possible.

[Trish Fisher]

The team is exploring ideas. Would using the toughbox make it harder for robots to push you around?

Does this mean that it is illegal to use a toughbox on this year's robot? I looked through the rules and I didn't see anything saying it was illegal, where would it be?

[Christopher149]

I don't think there has ever been a restriction on gear boxes (other than with window motors)

[nathan_hui]

Increasing the gear ratio (making the drive slower) would make it harder for someone else to push you around, but you run the risk of popping breakers.

Again, what Christopher said, though I think the PG71 was also restricted last year.

[Shane 2429]

nope my team has been using standard tough boxes for a long time and i haven't seen anything about toughboxes being removed from available usage

also yes they do slow you down quite a bit but if you want to play defense its whatcha gonna need

also easiest way to mount tough boxes drill holes in the casing mount that t the chassis and and then use all-thread and or a piece of 1in by 1in square bar and basically bolt them together. you need to do this because the amount of torque outputed will bend the bolts holding your gearboxes in place over time

also go steel its much better to know you wont have to strip apart gearboxes in the middle of a comp

[Ether]

Originally Posted by nathan_hui

Increasing the gear ratio (making the drive slower) would make it harder for someone else to push you around, but you run the risk of popping breakers.

Don't you have that backwards?

[nathan_hui]

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

[Jon Stratis]

Originally Posted by nathan_hui

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

It allows more torque at a higher motor speed... But your forgetting that the other robot is sitting there stalled. Stall = much, much higher current draw.

And seeing Ethers past contributions, like his recent tests on the speed controllers at Whirlpool's motor lab, I'm going to go with him on this one.

[pfreivald]

We used four 9:1 BB p80s on our Octocanum drive last year, then geared down a further 5:1 (net -- between the smaller traction wheels and a Gates belt with appropriately sized sprockets) when we got into pushing matches.

We got into lots and lots and lots and lots of pushing matches last year, and never once popped a breaker with a 45:1 reduction on four CIMs. Indeed, even with using pneumatics for the first time last year, and some extremely aggressive driving, we had better battery life than any other year thus far.

[Donut]

Originally Posted by nathan_hui

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

I think what Ether was pointing out is the part at the end about current. Increasing your gear ratio does increase motor revolutions relative to the output shaft, and increases torque. But this lowers overall current draw for the equivalent torque output, which would reduce breaker trips.

[nathan_hui]

I see. I guess you'd only see the current problem in a pushing match, or when you start flooring the accelerator. But for the purposes of the OP, extra motors (to the limit of the Toughboxes) shouldn't make a difference.

[Ether]

Originally Posted by nathan_hui

extra motors (to the limit of the Toughboxes) shouldn't make a difference.

Extra motors on a drivetrain make a difference when it comes to not popping breakers:

http://www.chiefdelphi.com/forums/sh...48&postcount=8

[Chris is me]

I think the KoP drive speed is very good this year and I don't see much of a reason to go more slowly, especially with the KoP drive using relatively precise belts. It's a good balance of speed and "pushing power".