Banebots Motor Question

[stundt1]

So my team and I was wondering if we use this kind of banebot (775) motor. We were wondering how sturdy the Banebot Gearboxes are? We are using two for our turret/shooter.


Thanks, Steve

[Ninja_Bait]

The gearboxes have a long lead time on them, and they are also prone to breakage - the gears strip before the motor reaches stall torque, they're shipped with screws that are barely long enough to hold the thing together, and any little bit of grit will jam them up.

We used the 550 gearboxes on an arm and it was a nightmare. The mounting holes on the sides were poorly tapped and they were very difficult to repair. We now have more 550 gearboxes than we'll ever need, because we bought so many spares. (Though, now as I rant, I realize this information may not apply to the 775 gearboxes - the quality may differ between series...)

775's only have a free speed of ~7000 rpm anyway. You'd be better off doing a one-stage spur gear reduction similar to the guts of a CIMple, because you don't need too much of a reduction for a turret. We're doing something similar, also using two 775's and found that a 3 to 1 ratio was sufficient.

[AlexH]

They are pretty sturdy, a lot sturdier than the old 36mm boxes. The most common failure point as in most other planetary gearboxes is the carrier plate sheers its pins that hold the planet gears. That only really happens when they receive a large shock load or are stressed too much in a cantilever setup.

[jason701802]

They're pretty good, but a cheaper and often stronger solution (that has no lead time) is to get a old cordless drill that uses the same size motor (775 in your case) and just do a drop-in replacement of the stock motor. People have been using Dewalt drills like this for years, even running CIMs through them (there's also a white paper detailing the required modifications), and last year we used the transmission from an old Milwaukee that we got at a used tool store for $30 or $40 and never had a problem. Some drills also have an anti-backdrive mechanism, which can be useful. The hardest part is mounting the transmission, but there are a lot of possibilities.

[ratdude747]

I will second the notion that the new BB transmissions are flimsy... they have gotten better, but the old black ended ones were so bad that improvement doesn't mean much.

I'd say use some AM planetaries and a couple FP motors... much stronger and powerful.

[diviney]

Originally Posted by ratdude747

I'd say use some AM planetaries and a couple FP motors... much stronger and powerful.

Unfortunately, all AM planetaries currently show out of stock (only 1 week after Kickoff).

[the man]

Originally Posted by Ninja_Bait

775's only have a free speed of ~7000 rpm anyway.

What? That's not what the data sheet said. It listed one at 13,000 rpm. And max power around 270 watts.

[AdamHeard]

A lot of misinformation in this thread.

In low reduction (25:1 and below is what we've used, maybe the 64:1 are good to) the p60s are great.

I wouldn't recommend a 775 due to their case short issues, but some teams have used them without issue.

The AM 500 sized motor, the "FP" and the banebots 550 are all more or less the same motor (all 500 sized motors) with similar power ratings.

[jason701802]

The case short problem is easy to get around, just mount the motor in an isolated environment. The plastic housing of a drill transmission or plastic somewhere else between the motor and the chassis works great for this. I would use the 775 motor before anything for any high-power scoring need (I'm assuming all 4 CIMs would be used up in the drive-train) as it is the third most powerful motor in the KOP (following the CIM and only 18W less than the -0673 FP) and its size allows it to handle high load and stall conditions much better and longer than a 550 or smaller motor.

[Teched3]

Originally Posted by jason701802

The case short problem is easy to get around, just mount the motor in an isolated environment. The plastic housing of a drill transmission or plastic somewhere else between the motor and the chassis works great for this. I would use the 775 motor before anything for any high-power scoring need (I'm assuming all 4 CIMs would be used up in the drive-train) as it is the third most powerful motor in the KOP (following the CIM and only 18W less than the -0673 FP) and its size allows it to handle high load and stall conditions much better and longer than a 550 or smaller motor.

The case short issue on the 775's is present right out of the box. Test the terminals with an ohmmeter to the case before using them. I agree all electronics and motor vents should be protected, and never cut or drill on your robot without covering components. Then test all systems before you're ready to compete.

[Ether]

Originally Posted by the man

What? That's not what the data sheet said. It listed one at 13,000 rpm. And max power around 270 watts.

Perhaps he was referring to the 775-12 instead of the 775-18. The 12 and the 18 are both legal for 2012. The 775-12 has a free speed of 7300rpm.

[Ether]

Originally Posted by jason701802

The case short problem is easy to get around, just mount the motor in an isolated environment. The plastic housing of a drill transmission or plastic somewhere else between the motor and the chassis works great for this.

Some have reported in other threads that the short can travel thru the motor's output shaft and find its way to the chassis.

[Ether]

Originally Posted by jason701802

I would use the 775 motor before anything for any high-power scoring need (I'm assuming all 4 CIMs would be used up in the drive-train) as it is the third most powerful motor in the KOP (following the CIM and only 18W less than the -0673 FP) and its size allows it to handle high load and stall conditions much better and longer than a 550 or smaller motor.

Here's some data, FWIW:

550-12 stalled at 12 volts: 70.5 ozin torque and 1020 watts heating.

775-18 stalled at 7.5 volts: 70.5 ozin torque and 406 watts heating.

[Kevin Sevcik]

The Banebots P60 gearboxes should be perfectly fine for powering a shooter wheel. As Adam said, you start running into problems if you use them in large reductions driving high inertias with shock loads. The failure point is actually where the output shaft meets the final stage carrier plate. It's a "Double-D" shaft/hole connection that's highly prone to deforming and camming out under shock loads. A low reduction gearbox into a shooter wheel just isn't going to have this problem.

As for lead times, last year was obviously horrendous with 20 day lead times or more. BB is currently stating up to 6 day lead times on orders. I think the lead time gets bad because they have such a modular system and they build each gearbox to order.

PROTIP: If you need a P60 gearbox RIGHT NOW, order all the individual parts for it and assemble it yourself.

Last year at the height of the 25-30 day lead times, we ordered wheels and spare P60 parts from BB and they shipped in 2-3 days. So I'm pretty certain you could just order all the various parts you need and they'd ship out much much faster.