Switching from Toughbox to SuperShifter

[DjScribbles]

I'm wondering if anyone who has experience with both can offer some insight, and some general drive-train advice.

My team would like to switch to a shifting gearbox, and I'm trying to weigh the feasibility of the task. From the images on andymark, the toughbox and supershifter look similar enough, however our robot is pretty tightly packed, and so any changes in the footprint of the shifter (dimensions, where the motor sticks out, etc) could be a deal breaker.

Also open to information on the Vex Ball Shifters.

Adding the pneumatics won't be a problem for us, and the programming portion is also fine; but from a mechanical standpoint, I don't want to throw down several hundred dollars only to find out they won't fit.

Gearing ratio suggestions are also appreciated (we're using 6" high grip wheels,4 wheel chain drive, with 1 cim each side), right now we're geared really low, and the kids love it, but the lack of speed when we need it is troublesome.

I've also considered gearing the robot up a bit and throwing another CIM in to help offset the gearing, will that give us more speed with the same push?

[Phyrxes]

For the last several years we have used Supershifters (each with 2 cims) and are currently looking at options for next year as our season is now over.

Why do you need the second gear ratio? Do you intend to drive in one ratio and use the other for a specific purpose? That is drive in "high" all the time and switch to low when you need more torque?

Alternatively if you just need to slow down your drivebase for specific maneuvering, like last year's bridge you can always implement software to limit speed.

Edit: Next year we are hoping to transition to a sheet metal drivebase and hope to better integrate our transmissions into our frame. We are currently looking at the WCP plates that use AndyMark internals but nothing solid at this point.

[Gregor]

Use 2 CIMs on each side, otherwise no point in a shifting gearbox.

[KrazyCarl92]

In general, the SuperShifter is intended to be used when wheels on your robot are direct driven by a live axle from the output of the gearbox. It sounds like you have a chain and sprocket reduction between the gearbox output and the driven wheels. This additional reduction could be why you feel that your robot is slow. We have the KOP tough box minis geared 10.7:1 direct driving 6" wheels to give us a speed of about 11 fps. To adjust the speed of your robot, you could also change out for smaller sprockets on the wheels or larger sprockets on the gearboxes.

I would definitely suggest adding 2 more CIMs to the drive train. This will increase available pushing power, increase acceleration, and reduce the amount of abuse the motors see. This alone will not increase your top end speed (maybe a very very small amount), but it will help you get there faster and could allow you to maintain your pushing force while doubling your speed through some other means (such as adjusting your gearing or sprocket reduction).

[JesseK]

If you can't CAD the replacement, I'd recommend against it.

For a rough estimate of good speed vs torque, search CD-media's whitepapers for "JVN Calculator". Add 2 more CIM motors to the current gearboxes and figure out a better ratio for your drivers.

No matter what, realize that if you think you're fast -- there's always someone faster. If you think you can push -- someone else can push harder. Conform your design to your strategy, not to an errant edge condition. In other words: where on the field do you think extra speed would be useful EVERY match, and how much less agile will that make your robot in the cramped places on the field?

[DjScribbles]

We want to be able to be fast while not losing our ability to win a pushing match.

If we get shifters, we will likely put the second set of CIMs on if we can spare the weight (or if we change gears in the toughbox). We are currently geared low (not sure how low, but we don't get pushed at all, and are pretty slow)

The general consensus seems to be gear up and add a CIM as an easy solution. However, I'm still interested in switching to shifters if it's possible to do on our robot (during an event), I'm looking for observations from someone who has made the switch; do the parts have the same attachment points/dimensions, are there any gotchas that we could run into, etc?

[Shane 2429]

In my personal opinion cut the weight out from somewhere else and put those extra motors into your gearboxes they are extremely helpful in a 1v1 or even 1v2 pushmatch and in cases like this year when the center of the field turns into a rugby scrum.

[protoserge]

I'd recommend "running what you've got". If you can get an extra CIM in there now, do it. Swapping gear boxes is not a trivial matter and may cause you to miss most of your practice matches (which you'd need to debug your new setup).

If you are confident enough in your ability to swap out the gear ratios, that may be beneficial as well. There are many teams running single speed gearboxes out there and are having a very successful season.

What are the strenths of your robot? What are the specs (dimensions and weight). Do you have a photo to help demonstrate the steps required for swapping the transmission out?

[midway78224]

Ive been running super shifters for a few yrs now. Our setup has always been to gear up the high gear where you run a 6:1 gear ratio. Then we run a 15:22 tooth sprocket from gearbox to wheel. We use the 6 inch first wheel. This give us about a 13.5 ft/sec in high and 4 ft in low. We have enough speed to do our gameplan and more then enough power to be in a pushing match. When we tested our low gear we pushed 325 lbs. If you have any more questions you can pm me and ill love to answer them.

[BJT]

The output shafts come out a bit toward the corners on a SS. They come out the middle of the toughbox. Could cause some headaches swapping them. The ball shifters output is centered like a toughbox

[Chris is me]

By no means are shifters mandatory this year. If you want a competitive drive that can push alright and still drive quickly, 4 CIMs is mandatory before you even start talking about shifters.

I would go with that, and try shifters in the off season. You don't want to take such a huge risk with such an essential part of your robot without experience, or at least a CAD model

What is your current gear ratio, wheel size, and wheel material? I'd be happy to suggest an alternate drive ratio to give your team a starting point.

[pmangels17]

If your TB's are chain driven, the regular shifter is probably a better option. The super shifter is geared for direct drive, or 1:1 chain.

[IndySam]

Like others I really really really (that's three reallys on the really scale suggest against changing this late in the game. Find a way to get those two other motors on there, you will be surprised at the difference.

AM has many ratios available for the toughboxes so you can also gear a little faster and still have good pushing power with those extra motors. At the same time you can reduce weight by using AM's aluminum gears and trading the box housings for the spacers also offered at AM.