BaneBots

I have seen lots of talk of the shorts in the BaneBot 775. Would it be a better idea, next year, to use two smaller motors instead of one 775, or is this problem with all banebots?

It all depends, I would much rather use a FP than any BB because it has more gearboxes it can adapt to, and last year BB had a horrible rate at witch they got there products to you. But we zapped our rs-775’s and they worked fine.

I would just use a 550.

It has the EXACT SAME mounting pattern as the FP, the power output is almost as much as the 775 (~250 vs ~265 watts), it’s slightly lighter (which unfortunately means it is more power dense and will heat up faster), and the output speed is comparable to a FP (within 10%, close enough to mate them directly).

Just so everyone knows:
The -0673 (2011) FP has more power than any single Banebots motor (I calculated 291 watts).

Do you think they will let us use more FP’s next year?

i wish they gave us more FP motors. we burned like 5 this year, but now that we know how to deal with them, i think that they could be pretty sweet. i think the rs550’s in a double doozy is a bout the best you can get short of a cim for complete durability and power.

*nominal max power ratings for 550 & 775: 247 & 271 watts respectively.

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My team, 1086 Blue Cheese, thought the same thing after having a CIM on our elevator at our first regional and tested with the single FP between our first and second regionals. After finding that the FP stalled we tried the Double Doozy on a custom gearbox we made, which was basically a flattened out ToughBox due to size restraints in the space around our elevator. Originally we had problems with the pinion gear teeth sheering off, turns out they were created out of a bad batch of metal. Of course AndyMark express shipped us 5 or 6 more out of a good batch and we never had one sheer again. Back to the point of this post, we found that under the stress we put our 2 BaneBots 550’s under in our elevator was enough to burn them out about every 2 to 3 matches. The problem even continued when our elevator had two constant force tension spring helping each stage up individually. Hope our experiences with this help!

Patrick Brew
First Team 1086 Blue Cheese

At this time, we have no idea what motors we’ll get to use next year. I doubt that we’ll get known defective motors.

We don’t even know if we’re allowed to use aluminum next year (1714 FTW)

If we get guaranteed good parts, the KoP may jump to $7K. :eek: :yikes:

wow. two smilies in a row. I better take my temperature.

Wait what no aluminum?!

Yep totallly illegal and not allowed :stuck_out_tongue:

-RC

Good thing were learning how to use carbon fiber & polyurethane this off season :wink:

Our story is exactly the opposite of this. We had one RS-550 on our 4 bar arm all year long. The 256:1 gearbox wore much faster than the rs-550. During one match, we had part of the surgical tubing break, and the rs-550 let off a bit of smoke and heated up because the far to intense for the gearing. The motor still ran strong for 15 more matches.

The rs-550s will get hot if you put them in a situation where they endure ~>50% load for 10-15 second intervals with short breaks inbetween. However, we stalled the motor (by accident) giving it ~20% power for 15 minutes or so with only mild heating of the motor.

Did you really mean you gave it 20% power?

At 12 volts at stall, you are giving it 1020 watts of power. 20% of that is 204 watts power. I doubt the 550 could dissipate 204 watts for 15 minutes with only mild heating.

Maybe you meant you gave it 20% voltage?

20% of 12 volts is 2.4 volts. At 2.4 volts at stall, you are giving it 41 watts of power. Even at that lower number, the 550 would get pretty warm after 15 minutes.

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Any company that mass produces a known defective or dangerous KOP item and them refuses to support the repair and/or replacement of that item should be unceremoniously DUMPED as a sponsor. And if FIRST invites such sponsors back then shame on them.

It is pure coincidence that I am writing this opinion in this particular thread.

one way to prevent motors burning is to put in some software protection, if you have CAN on that motor you can limit the amount of sustained current eg, if more than 60 amps is going to the lift FP for more than .25 secs with no increase in speed, then kill it. we did this on two motors i believe, our roller and our lift, while the FP was a little harder to prevent from smoking, we stalled our roller every time we picked up a tube, and never had an issue with it.

The Banebot failures have nothing to do with stalls, at all.

I don’t think he was referring to the case-short defective motors or overtorquing transmissions.

His suggestion seemed to be directed toward preventing damage to a non-faulty motor.

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We ran two 775 on our robot without issue. Luckily, out of 5 or so motors that we got, only one had a short, and the two that we did use never developed shorts. But, even if they had shorted out, it is unlikely that they would have caused much trouble at all since they were isolated from the frame by fisher-price transmissions.
Fisher price transmissions, conveniently, already have mounting holes for a 700 sized motor. Also, since the gears and casing are plastic, and not metal, the motors are isolated. It was plenty powerful too. At one point we bent a 5/8" anodized aluminum jackshaft and split a steel sprocket into three pieces when our robot got hung up on the scoring grid (fixed in between matches by replacing the damaged parts and by adding a polycarbonate plate under the arm so it would slide off the pegs).

People seem to really get caught up in xyz motor being so fantastic, and yxz being crud.

People need to think of motors purely as power sources, with some varying factors. The torque and speed output obviously determine the power, and are useful characteristics to know.

The other useful characteristics, are it’s thermal mass/ability to dissipate heat, it’s friction/resistance which cause it to generate heat, and then obviously any sort of special notes about the motor (current limiting breakers built in, a built in gear reduction that adds friction, etc…).

I know this is a rough approximation, and there are some “lies” here, but it’s a decent way for begginners to understand.

Assuming the 775 had no manufacturing defect, the FP, 550, and 775 were actually all pretty $@#$@#$@#$@# similar in terms of power production. The 775 could be considered the “better” motor there as it is much heavier, and is much more capable of dissipating heat. One could argue the smaller motors are better, as they weigh less for the same power. It really comes down to what you need them for.

People also seem to assume the small motors aren’t durable, which may or mot not be true depending on how you define durability. They certain can’t handle high levels of repeated stalls, but you shouldn’t design them to! They are very powerful motors, and can do a lot of work without ever getting hot if your system is properly designed. As Chris on 330 says, run them fast! which means high gear reduction, so the motor is spinning closer to free speed.

We picked hte 775s in all four places this year, and had some issues with case shorts. We had zero issues in terms of burning or damaging them. Assuming it stays the same, the 550’s thru a cimulator will probably be our preffered motor.

I also forgot to mention that banebots does not make these motors. They are a standard sized motor (395/540/550, etc…) that many different manufacturers will make, for many different purposes. Within each size, there are commanalities in the shafts, mounting holes, etc… It’s not rocket science to interface to any one of these gearboxes, considering the absurd amount of options on the market for them.