Banebots RS-775 Case Short
 

We have a Banebots 775 motor with its power leads shorted to the case. You can imagine why this would be an issue. We are not sure whether this is the one from the kit or the additional one we ordered.

I've seen one other team who posted about a problem with this... (http://blog.iamjvn.com/2011/02/jvn-b...75-motors.html)

Is anyone else having this issue? If you have NOT run your 775's yet, could you check them and see if they have this problem? It would be nice to know if they are DOA or if they were damaged while running in the robot.

Re: Banebots RS-775 Case Short
 

John mentioned it in his blog post, but we saw this on some brand new out-of-the box motors, too. It wasn't limited to just the ones we had already run.

Re: Banebots RS-775 Case Short
 

1114 has seen the same thing with some of our unused and used 775s.

Re: Banebots RS-775 Case Short
 

On a semi-related note,

We've also run into an issue where the "red dot" that presumably indicates where the positive terminal of the motor is is not consistent between the RS-775s.

We have a single gearbox that mates to two RS-775s, and had them both wired according to the red dot, and when we powered them up, they ran in opposite directions...

Re: Banebots RS-775 Case Short
 

25% of the unused, still-in-the-box 775 motors we tested were case shorted.

Re: Banebots RS-775 Case Short
 

Zero of our 15ish were defective, but not have been installed and ran on a robot.

Re: Banebots RS-775 Case Short
 

Although we aren't using any on our bot I'm gonna check ours just for kicks.


Side note: it really is good practice to check all motors for such issues before you use them, prevents nasty little surprises sometimes. I never apply power to a new motor (in FIRST or otherwise) without testing it for ground faults and other problems.

Re: Banebots RS-775 Case Short
 

Hmmmm.... Just our luck I went and checked our 3, 2 of which were conductive. What exactly makes them "bad"? I have not heard why exactly this a problem.

Re: Banebots RS-775 Case Short
 

Got in 3 today crammed in a flat-rate box without much padding. None have case shorting issues.

Re: Banebots RS-775 Case Short
 

Imagine two of your motors have a short to the case, and they're mounted to metal parts of your robot that connect...interesting things might happen.

I think it's also against the rules to have any power applied to the metal parts of the robot.

Re: Banebots RS-775 Case Short
 

Arrgh... 3 of our 10 were shorted to case. Thanks for saving us some trouble. Has anyone tried to go through the Banebots RMA process yet?

Re: Banebots RS-775 Case Short
 

Could someone please post the steps to check the 775s for a short?

Is there a fix? Or do the motors need to be returned.

Thanks

Re: Banebots RS-775 Case Short
 

3/7 of ours were shorted

Re: Banebots RS-775 Case Short
 

Use a multimeter to check the resistance between one of your motor leads and the motor casing. If it is conductive, you've got a problem.

We pulled one apart and tried to fix it, but no luck.

We haven't done the RMA process and probably won't bother (the motors have all been modified for use). The ordering (waiting) process was painful enough.

We had one of these motors (via AM Planetary) driving the same gear as a CIM. One of my freshman was wondering why the "gear was sparking." I told him it was normal to see sparks coming out the back of an open motor like the 775. He corrected me -- "not out the back, on the front... on the gear." Ugh -- that was when we first noticed the issue.

-John

Re: Banebots RS-775 Case Short
 

You gotta love those young eyes!

Re: Banebots RS-775 Case Short
 

We were lucky for once. 1 out of 6 bad, but it was a spare.

We also have one with the screw threaded slightly out of square, when mounted in a Cim-U-later, it binds the motor.

Re: Banebots RS-775 Case Short
 

So far, no problems for us.

-Nick

Re: Banebots RS-775 Case Short
 

I just got off the phone with BaneBots.

They believe the problem is caused by a small amount of debris in the motor possibly introduced during manufacturing.

They have had success with several motors in house when they apply 12V between the motor lead and the case. This zaps the debris and you should be good to go. You might have try this with both leads depending on where the debris is.

I will try this on our 2 shorted motors tonight and post our results.

-David

Re: Banebots RS-775 Case Short
 

Thanks for the info. I'll give this a go as well and post the results.

Re: Banebots RS-775 Case Short
 

Would it be legal to open the motors for the purpose of cleaning them as long as they were not modified in any way?

I know it would be a difficult task, and might end up damaging the motors, but applying 12vdc across a known short is not what I would consider a safe option let alone a good fix. More debris could still be in the motor, and the frag from blasting the original offender is still in there and becomes a complete unknown. It would be like asking Murphy pay a visit at the worst possible moment.

Re: Banebots RS-775 Case Short
 

I agree it's not the safest option, but you could always try shorting it with a source that does NOT easily supply 500 A...

Re: Banebots RS-775 Case Short
 

I agree, this "fix" makes me a little uneasy. I am just repeating what they suggested.

I figure since our shorted motors are useless anyway, it is worth a shot. BaneBots told me to give them a call if the "fix" doesn't work or there are more problems.

I would try this with a smaller battery or a current limiting power supply. They told me that it should only take a few milliamps to zap the debris/residue (at one point the BaneBots rep mentioned "manufacturing residue").

-David

Re: Banebots RS-775 Case Short
 

David,
I just think this method is bad on so many levels. Did they give you any idea on what form of debris may be present that they are trying to zap? If this is metal flakes left over from balancing operations, shorts to case are going to be the least of the problems. Depending on the size of the debris, this may be a permanent fix or a permanent short.I won't have access to a motor for a while, can you examine one of yours?

Re: Banebots RS-775 Case Short
 

If someone does attempt the zap, report back on your findings ASAP, I know a few teams who would be interested to know if this "fixes" the motors or not.

-Brando

Re: Banebots RS-775 Case Short
 

I gave both leads about 100mA through the case for about 3 minutes each. Nothing. I'm debating if a big burst (like, say, a battery) is worth trying. I can't really imagine it is.

Re: Banebots RS-775 Case Short
 

Team 85 gave the BaneBot suggestion a try to rectify the issue with the 775 motor and we are good to go!

Re: Banebots RS-775 Case Short
 

Could you check the continuity again after using it while slowly turning the shaft by hand? I'm wondering if it is an intermittent short.

Re: Banebots RS-775 Case Short
 

Did what you asked and we are still good to go

Re: Banebots RS-775 Case Short
 

Well <r47> states

I would take that as a "no" just to be on the safe side.

Re: Banebots RS-775 Case Short
 

~50% of our motors (atleast 7) had the Case Short.

We performed the technique suggested by Banebot, with a standard FIRST battery, and "fixed" the issue on our motors.

I wasn't involved in the process, but I think they just swiped the positive lead across the motor case to limit any additional damage. It took a couple of swipes to totally eliminate the short.

Not sure what the long lasting effects will be.... we plan to run these motors on our practice bot to see how well they work.

We are only using (2) RS775 on the our robot, and I think we had (4) good ones...so those will go on the competition robot.

Re: Banebots RS-775 Case Short
 

We were 3/3 with the "zapping" technique. We had to do it a couple of times to max out our ohmmeter on a couple of motors. We rotated the shafts by hand both while "zapping" and while verifying the open circuit.

Re: Banebots RS-775 Case Short
 

I'm sorry, but working or not this is an extremely bad suggestion. What if that small bit of 'residue' is actually a sizeable chunk of metal? You can potentially spot weld the battery leads to the motor and cause someone serious injury. I've seen this happen when someone tried something similar with a fan.

We'll try something tomorrow, but we'll do it through a 40 amp snap action and see if we have any luck with that.

I will also add that this will likely be the swan song for the use of banebots hardware for our team (unless we're forced into it by FIRST continuing to use their motors). After '07, the transmissions, and now incredibly poor quality control on their motors, we've had enough.

We have enough build season issues without having to RMA things we've bought and redesign major components because of a lack of timely shipping.

Re: Banebots RS-775 Case Short
 

Adam,
Was there fireworks when you applied the battery? Please note that TU11 was released tonight that modifies the 'do not modify' rule.

Re: Banebots RS-775 Case Short
 

Al,

I was working on another part at that time, but from what I saw there were no fireworks. It actually appeared "easy" to do....but I am sure they were taking precautions to attempt to limit the risks.

I do agree with Tom Line, its not the smarted thing to do...and that there are potentially some really bad things that could happen.

I would advise that people attempt to do this at their own risk.

Hopefully we can come up with a safer way to "fix" these motors.

Re: Banebots RS-775 Case Short
 

There were no fireworks when we tried this. For motor #1, there was a very quiet "pop" sound at first, then nothing. For motor #2, there was a bit of an arc when the motor lead was attached, then nothing. For motor #3, there was no visible or audible reaction at all. The suggestion to use a 40A breaker is a good one.

2 of the 3 775s on our first robot were affected by the case short. Prior to doing the "zapping", we were measuring ~8 megaohms between the negative battery lead and conductive parts of our chassis. After removing each affected motor and applying the fix, we now max out the ohmmeter (>30 megaohm resistance).

Re: Banebots RS-775 Case Short
 

Hi all,
I checked our 3 motors last night and found 2 of them to be shorted, if you call 6 ohms shorted.
I set up a smaller battery, and a 40A breaker and proceeded to 'zap' them by putting one wire on the terminal and one on the housing.
One motor showed no sign of a spark and was healed and works fine now, and the other one showed a bigger spark on the first touch, but no sparks on subsequent tries, unfortunately, it was only semi healed in that it continues to have 300-500 ohms of case to terminal resistance.

While I'm happy to get one motor working, I have to say that this is the craziest fix, and I'm not happy with having to have done it.

If you try it, please be safe.

Mike

Re: Banebots RS-775 Case Short
 

Has anyone be able to see the debris? Can you describe it? What I am trying to determine is this a permanent fix or is there more of the debris just waiting to bite us in competition. We need a permanent and reliable solution.
For others, a 10K or higher resistance any lead to case seems to be OK, megohm is better. The six ohms reported is definitely bad, 500-600 ohms is still in the bad region as well.

Re: Banebots RS-775 Case Short
 

I did not see any debris before, during, or after the zapping. I will continue to monitor for case shorts as we continue to do testing and driving.

BTW, although in my prior post I mention 8 megaohm resistance to the frame (from negative battery terminal to the furthest point of our arm), resistance between the motor terminals and the motor case itself was below 1 ohm prior to the zapping (now it is >30 megaohms).

Re: Banebots RS-775 Case Short
 

We had 2 of 5 motors with case shorts. One was 1k ohm and the other was about 2 ohms. We applied 12VDC from a current limited power supply set for 25A max. On the 1k ohm motor, the problem cleared immediately. The 2 ohm motor let loose with some nice blue sparks, but then was good.

We remeasured both motors and both still had some high resistance (~20K ohms) to ground. We than ran each motor for a few minutes while applying + to the case. We then repeated this with - to the case. Both motors are now showing >20M ohms. I guess that's a fix!

No debris was seen at any point in the proceedings.

However, I must echo the points above about being careful when doing this as a short which does not clear could be very dangerous, particularly if your voltage is not current limited to a "safe" level.

Banebots has really "missed the boat" on this years offerings to FIRST.

JW

Re: Banebots RS-775 Case Short
 

Thanks for all of the info -- we'll get our extra 775's in after ship date, so we'll have to test things then. The KOP 775 was fine though.

This makes me weary of BB. We didn't have the problems in 2007 that others had (custom plates), yet between this and our eaten 256:1 gearbox in 2008 I think we'll take pause on our gut reactions to use the BB motors in future years.

Re: Banebots RS-775 Case Short
 

It seems like our attempt at the zap was successful on one motor. We still have one other motor to try later tonight.

I ran the motor for some time and it is still operating as it should. Before the zap, 4 ohms, after the zap, open circuit.

-David

Re: Banebots RS-775 Case Short
 

Everyone,
I am attempting to find the type of debris that teams may encounter and where it might be located in your motors so I can pass this info to inspectors. Believe it or not, some teams don't visit CD for the latest discussions. Electrically neutral frames are a line item for inspections that will need to be dealt with during the season. Thanks for everyone's help on this issue.

Re: Banebots RS-775 Case Short
 

I was not able to see any debris in the motors we fixed today.

However, one was a little more 'substantial' than the other, we got sparks about 12 inches out the front of the motor and the negative lead spot welded itself to the motor case.

The motor does appear to be fixed though. We got a nice round of 'oooooooooooo' from the audience when we did it too. ::safety::

Re: Banebots RS-775 Case Short
 

Tom,
That was more the effect I was worried about. From the angle of the trajectory would you say that the flames came from the end of the motor (brush assy) or from the commutator? I am guessing that is the only two places where debris would collect and still short to frame. Or could it be excess solder where the windings are tied to the commutator?

Re: Banebots RS-775 Case Short
 

Actually, if I were to guess I'd say neither. The sparks actually exited the front of the motor through the holes that surround the axle. Had this been a short near the brushes or commutators, I would have expected them to come out the back (where I had my hands...).

That doesn't make much sense to me, because I'd expect the wire to be covered in varnish and not be conductive except at the locations you mentioned.

Re: Banebots RS-775 Case Short
 

OK,
Now I am really confused. I haven't taken a 775 apart. I wonder if there is winding terminations at both ends of the armature.

Re: Banebots RS-775 Case Short
 

For what it's worth, 3 of our 8 775s had a short to case. I had marked them as "bad" and was going to pitch them in the trash. After reading here about the zaping procedure I figured what the heck and gave it a try. The zaping procedure seemed to fix all three of our motors, however, we will still not be using them in competition and are considering not using any 775s at all and changing our plan to use 550s and the FP. I am pretty disappointed in BaneBots over the years and this just adds insult to injury. :mad:

Of the 3:

The first 2 sparked somewhat spectacularly both apparently from the larger holes near the back/terminal end.

The last 1 produced almost no spark at all and was only visable as a tiny (~1/16") arc when the wire touched the case. No sparks apparent coming from inside the motor.

The first one we zapped with the lights on and sparks were clearly visable even in a well lit area. For "effect" we cut the lights off on the last 2 and the first one sparked nicely and the last one was the one with almost no spark which probably wouldn't have even been visable if the lights were on. On all three it only took one zap to fix the motor. The procedure was about as simple as it gets. I took a robot battery plugged in an Anderson connector with bare wires, held the red to the red terminal on the motor and touched the black to the case. No breaker involved. For as strange of a "recomended fix" as this is it seemed to work. The second motor we did does have a slight burned black line on the case where the wire touched. Other than that no other obvious signs on the outside other than where I wrote on them with a Sharpie.

Re: Banebots RS-775 Case Short
 

You left out the most important step:

I checked to make sure everyone in the room was wearing their safety glasses.

Re: Banebots RS-775 Case Short
 

Yeah, and we made sure there were no flamable liquids ar vapors nearby as well. ::safety::

Re: Banebots RS-775 Case Short
 

I'm super curious as to what exactly is shorted in the first place, and is blowing apart inside during this procedure. Can someone who has some 775 spares sacrafice one for curiosity's sake?

Re: Banebots RS-775 Case Short
 

2 of our 6 RS-775s had case shorts as well. We tried the case-to-lead zapping procedure recommended by BaneBots, and it remedied the problem on both. We did have to zap one of them twice after we spun it a few times after the first attempt. I wish there was a safer way to fix this without taking them apart.

-Nick

Re: Banebots RS-775 Case Short
 

I keep forgetting to measure ours, we just have the one that came in the kit. If it's shorted, I'll take it apart. If I remember. We happen to be kind of busy building a robot, so I'm sort of distracted when I'm at the school.

Re: Banebots RS-775 Case Short
 

We just two more yesterday and checked them. They are both good! We have to earlier and they are good two.. I guess we got lucky

Re: Banebots RS-775 Case Short
 

Our kit motor and one of the three we ordered had the case short. Luckily the decision was made to use a Window motor on our arm instead. The other two motors were installed on CIMulators and will be put on our drivetrain once we find some CIM keys...

I'm really hesitant to do the battery pulse fix on these motors. We'll see.

Re: Banebots RS-775 Case Short
 

Hey Jim, You have used that excuse in the past.

Re: Banebots RS-775 Case Short
 

Thanks for reminding me to make a reminder for myself....hopefully I'll see it when I write some other reminder on my hand today.

Re: Banebots RS-775 Case Short
 

Ah, the signs of spring are in the air, preship craziness. I am off to playing field and shop for a day of fun and fluorescent light.

Re: Banebots RS-775 Case Short
 

We got lucky, our kit 775 has less than two ohms resistance between the case and terminals. Good thing we didn't try to use it. We did not try to clear the debris with the battery trick, but did take it apart, and aside from slightly chipping the brushes while removing the end cap, did not see any debris. The windings are almost a dead short to the motor shaft (measured between shaft and commutator). Any suggestions for what to do now? Maybe we could unwind the windings? the soldering job doesn't look very good, but it also doesn't look like it would be causing problems. I took some pics but don't have means to get the pics off my camera here at school.

Re: Banebots RS-775 Case Short
 

I pulled our Banebot 775 apart before I read about the fix. The connection to the case is through the rotor assembly to the rotor shaft. A direct short can be read between the commutator and the shaft.

There is no obvious debris. I could speculate what happens during the "manufacturing process," but until Banebots is more forthcoming with specifics, I don't think we will really know. The rotor assembly is pressed then varnished, without extensive forensics, I would say the exact problem will be hard to get at. There are some balance holes machined out of the stack, so maybe that is the source of the issue.

After I reassembled, I applied the battery current across the terminal and case. There was a minor spark and now the motor is fine. We can't use it in competition since it has been disassembled, but it will be perfectly acceptable for practice.

If anyone knows if Banebots is replacing these it would be nice to know.

Dan Glenn
Mentor
Team 1622 Spyder, Poway High School, California

Re: Banebots RS-775 Case Short
 

picture of armature.

Re: Banebots RS-775 Case Short
 

Using a better ohm meter, although the test leads themselves have a bit of resistance (about 0.1 ohms when shorted).

Re: Banebots RS-775 Case Short
 

Hey Jim,

That is one fine voltmeter ya got there. Have you tried getting it assessed on Antiques Roadshow?


Oh, BTW: I think the calibration date is a bit overdue :-)

Re: Banebots RS-775 Case Short
 

I was just noticing that it was last calibrated when our youngest sons (twins) were still a twinkle in my eye...and they're in college now....

Re: Banebots RS-775 Case Short
 

We got a response when we sent in an RMA request that this was a known issue and that they would not replace the motor. They simply said to apply some voltage across the case and a motor lead to burn off the manufacturing debris.

Re: Banebots RS-775 Case Short
 

Same here: "If it is an issue for your application it can easily be eliminated by passing a modest amount of current from the terminal to the case."

As far as I'm concerned, this is not a FIRST legal motor if it conducts current to ground. Worst customer support of any FIRST KOP supplier. I hope First thinks twice before using these motors in KOP again.

Re: Banebots RS-775 Case Short
 

Our kit 775 also had 2.3 Ohms between terminal and the case on BOTH terminals, and we'd been using it off and on for a few days. We shorted the terminals to the case with the battery (one at a time) and now we're seeing 126kOhm between terminal and case on both terminals. Our other 775 that we were "gifted" from 3320 (The M&M's) had 3MOhm between terminals and case.

I was disappointed that there wasn't as much of a fireworks display as others seem to have experienced when we did it. :o

-Danny

Re: Banebots RS-775 Case Short
 

Show me where else you can get these motors and decent planetary gearboxes for them at the same price. If you want great support behind the products, would you also want to pay double the price for them, so they could hire more people to support them? I'm sure they probably are not a large company. Yes, they've had long lead times and a few issues, but give them a break. We could be using Bosch drill transmissions... You know back around 2002, there was no BaneBots, there was no AndyMark, there were no CIM motors with a nice keyed shaft, and we were restricted to purchasing parts only from one very overpriced supplier. Teams still made great robots.

Yes, the BaneBots products have a few flaws. But, it's up to the designer to consider those shortfalls, and design around them. For the price, their products are great. I was quite happy to see the BaneBots motors (especially the 775) in the KOP this year, and I hope they are here to stay.

Re: Banebots RS-775 Case Short
 

With the exception of this large design flaw, the 775-18v is a great motor that I hope we get to use again and again. The decision to include the 18v version and to run that at 12 volts was really smart!

Re: Banebots RS-775 Case Short
 

We don't know yet whether it is a design flaw or a manufacturing (quality control) problem.

Re: Banebots RS-775 Case Short
 

I think we do know that it is a manufacturing problem:

If you do execute the fix, the motors are fine. Our problem is, we opened them up before we read about the fix, now we are left to buy new ones or design around the motors.

Dan Glenn
Mentor, Team Spyder 1622
San Diego, CA

Re: Banebots RS-775 Case Short
 

I guess my point was this: Just because the debris is introduced during manufacturing doesn't necessarily mean it is a manufacturing problem.

If the design is such that no reasonable (cost effective) manufacturing process would be capable of avoiding unacceptable debris, then it is a design problem.

Re: Banebots RS-775 Case Short
 

The insides look like countless other motors....but without seeing the complete design documentation, and seeing what the actual problem is, it's guesswork. My guesswork says manufacturing problem, either with the process or materials not meeting spec.

I should unwind the thing and see if there's really any debris, or if the insulation on the wire is damaged. Although it's probably gonna be hard to tell.

Re: Banebots RS-775 Case Short
 

I cut all the windings at the commutator connections. The first winding (there are 5, overlapping) is the one that is shorted. So I guess I'll take them all off and see what I can find.

Re: Banebots RS-775 Case Short
 

I found the short. The first winding on the motor was touching the amature core, at this corner. I found it by connecting my trusty 77 DMM to one end of the wire and to the shaft, and it beeped until I got this part of the winding loose. It was very difficult to remove the wire here. As soon as I pulled it loose, the beeping stopped.

My take on it: I did not find any "debris" in this motor, but it also had a complete short of winding to armature core. If you have a completely shorted motor (less than 5 ohms resistance from either terminal to case), then I'd suggest you do not use that motor. If the resistance is considerably higher, then you might possibly have a "debris" problem, and if you "fix" it by blowing it with high current from case to winding, the motor might be fine.

btw the white stuff is glue that is used to hold the plastic fan in place.

I hope this little forensic exercise was helpful!

Re: Banebots RS-775 Case Short
 

First off, Jim, thank you for taking the time to look into this issue in such detail and giving us this information.

Here is my concern based on what you found:

If this is in fact the root cause, and common to all the 775 motors showing this fault, then the "fix" is only truly is a poor solution.

Here is why I say that. For the "fix" to work, the current path has to be through the terminal(s), through one of the brushes into the commutator, through the short and into the armature then finally through the bushings/bearings to the case. The current that can possibly blow this short open, also has the potential to damage the brush/commutator contact point as well as the bushing/bearing assembly. Yes, the brush/commutator are designed to carry high current, but the bushings/bearings are not. (I use the term "bushing/bearings" because I am not sure of exactly how this motor is actually assembled.)
Now, if enough current is passed to open this short, then I can almost assure you that it not passing through the bushing/bearings without having a detrimental effect. How much damage is being done is indeterminable at this point. How long will these motors run without failing is also an unknown.

I for one would rather replace the motor with a "known good" one, than risk it failing at the most inopportune time.

Re: Banebots RS-775 Case Short
 

You're welcome.

The motor uses oilite type bushings, it looks like they're plenty large enough to conduct a lot of current without damage. I'd be more concerned about the brushes and commutator than the bushings. But I would be even more concerned that "fixing" a shorted winding will melt the wire and open it, so the motor will only be running on 80% of it's windings.

I looked closer at the armature, and I think the issue is that the wire was making contact at a corner of the winding, where it wraps around the core. The green insulating paint is deformed where some of the windings contact it at the corner, and in one spot metal was showing. I think that either the paint was not fully dry, or the wire was pulled too tightly as it was wound on the core.

I've enjoyed taking stuff apart ever since I was a little kid. I think it's part of the engineer mentality.

Re: Banebots RS-775 Case Short
 

This is worth a test.

And if it comes back that that's how the fix works—by severing a winding—then BaneBots should damned well have disclosed that fact. (Not knowing is negligence, not an excuse. I want to give them the benefit of the doubt: maybe their supplier was lying to them about the presence of debris, or maybe this one motor is not representative of the failure mode that they'd encountered. But if BaneBots came up with the fix, it's their responsibility to explain the issue and resolution accurately and completely.)

I don't know the nature of BaneBots supplier arrangement with FIRST;* if they're donating the parts for free, or heavily discounting them, then I understand that we shouldn't ask too much of them. But if FIRST is a paying customer, I think that it would be reasonable to forward BaneBots a summary of the motor rules, with the explanation that all FRC teams are very strictly limited as to what they can and can't do, and that if BaneBots wants to do business, they need to provide somewhat better service. (Aside: actually, I support the idea of being able to repair parts in principle, so the recent team update was a good result. There are too many high-value or high-lead-time items that can fail and seriously disadvantage a team. As long as it's clear the repairs don't rise to the level of a significant functional change, I'm on board.)

This is not to minimize the impact of the corrective actions BaneBots has taken in the past with regard to their products—I'm sure that resolving those issues was stressful and complicated, not to mention costly. But the fundamental flaw those times was misspecification: for example, they hadn't provided accurate information on how to safely use the gearboxes. (Granted, in the case of the bad CIM boxes, if they'd done so, they wouldn't have sold any for drivetrains, because they would have had to publish specs indicating their parts were unlikely to be up to that task.)

In fact, let's consider the problems associated with BaneBots products in FRC applications (am I missing or mischaracterizing anything?):

• 2007: Failures reported on BaneBots high-reduction planetary gearboxes (36 mm & 42 mm sizes); BaneBots has since updated their specifications to warn against high-torque load cases, and released new lines of gearboxes that are apparently more durable
• 2007: BaneBots CIM gearboxes with defective planet carrier plates; BaneBots designed replacement (more durable) carriers
• 2009: Without advising purchasers, BaneBots substituted RS-545/RS-385 motors that didn't match the ones depicted on their website (listed as FIRST-legal), and more importantly, were different from the RS545PH-5125F model in the KOP; never explicitly resolved, but hopefully never happens again (we never found out what the specs on the plastic-endcapped RS-545 motors were)
• 2011: RS-775 motors are frequently defective as supplied
• 2011: Lead times of up to 3 weeks on some gearboxes

So what's the root cause here? Want to bet that it has something to do with not testing their products adequately for FRC applications? And maybe there's some unfamiliarity with just what they're being asked to provide, as an FRC supplier—e.g. have enough stock of the right motors (or be able to get them fast), and communicate with FRC HQ when your supply chain breaks down (instead of trying to pass off non-compliant materiel, or delaying shipments). (It's possible that FRC HQ hasn't communicated these expectations, perhaps because they see things differently; if that's the case, I'm interested in their position on the matter.)

Part of being in business is managing inventory and deliveries—and while it's a company's prerogative to choose to keep low inventory and impose long lead times, it's their customers' prerogative to not choose that company the next time they have a critical project. Similarly, while their low prices are great, I'm certain that the majority of FIRST teams are willing to concede that a little extra cost to ensure quality in a critical component like a motor or gearbox is a good thing. After all, isn't that a big reason why AndyMark products are so popular, despite their often-higher prices? (Along with excellent service and innate familiarity with FRC.) Isn't that why people will pay $25 to $28 for a CIM motor that virtually never fails?

Maybe BaneBots needs to concentrate on being a little more like AndyMark or IFI, or else consider taking a step back from their current role as a critical FRC supplier?

*Why don't I know this? Is there really any harm in disclosing this fact? After all, the benefit of disclosure is that it calibrates the community's expectations.

Re: Banebots RS-775 Case Short
 

Another bright side: They don't sell airplanes :-/

BTW - the one's we used the ZAP fix on do not perform as well as the ones that tested OK. Anyone else notice a performance hit?

Re: Banebots RS-775 Case Short
 

Yes, our programmers have commented on that fact as well.

Re: Banebots RS-775 Case Short
 

Do you have any quantitative data, or is this mostly a perception ?

Re: Banebots RS-775 Case Short
 

Is there anyone who has access to a function generator or an oscilloscope who would be willing to test the locked-rotor inductance (and resistance) of a few "fixed" and non-defective RS775's ?

http://www.chiefdelphi.com/forums/sh...ad.php?t=90246

Re: Banebots RS-775 Case Short
 

A picture of what I suspect is the problem with the motor I disassembled.

Notice the "dents" in the green insulating paint at the corner of the armature core, where the wire wraps around it. There are two places where the metal is showing through. The wire is insulated with a thin coat of some type of paint also (in the old days, it was varnish, I don't know what these ones use). It doesn't take much to scrape the insulation off the wire, and have it short.

Re: Banebots RS-775 Case Short
 

Jim,
Thanks for all the CIS on this motor. As Jack pointed out, my next question (assuming all of the motors have a winding to core short) is does the fix burn open one of the winding? In his case it seems as if it does. In your original photo, I also noticed a solder blob buried in the windings. That is a pretty bad job no matter what. Every student on my electrical team can do a better job than that.

Re: Banebots RS-775 Case Short
 

Al, I expect that motors with a low resistance short have the problem I encountered, and it's likely that applying a lot of current will melt a wire. But I have no idea if there are other things wrong with other motors. I only had one to take apart. There are a lot of things that can go wrong when building an electric motor within strict cost constraints.

Re: Banebots RS-775 Case Short
 

2 out of 3 bad for us...any chance the company actually tests their motors before they ship them out now??? Not comfortable with the "fix" if it reduces the performance as has been seen with some cases.

Re: Banebots RS-775 Case Short
 

IDK - Why test? They don't care what they sell us. I ordered two for spares and specifically asked for two that tested infinite resistance between leads and case. They sent two that tested 56k and 32k.

I will NEVER do business with them again!!

Re: Banebots RS-775 Case Short
 

Jack, et al,

There is not a motor in the world which will pass that criteria.

Most of us spec out motors to a specific criteria form a recognized approval agengy (such as UL) called a Dielectric Withstand Test. The parameters for such a test would be that the device withstand a voltage (such as 2 times the rated maximum voltage plus 1000V) with less than a specified current (such as 1 mA) for a specified time (such as at least 60 seconds).

But we aren't buying UL listed motors, are we? We are using motors that are factory seconds or discontinued items that have been donated (or sold at a deep discount) to FIRST.

I'm not defending Banebots. This case shorting issue is not acceptable. However, you get what you pay for.

BTW, please check with your electrical lead mentor before attempting a DWT as you need specific test equipment and the test degrades the insulation being tested.

JMHO,

Mike

Re: Banebots RS-775 Case Short
 

I realize you get what you pay for. The problem is we really have no choice when FIRST limits the brand/model and number of motors and the brand with the most choices has such poor quality product. We don't mind paying more for better product...just wish we had the choice to do so.

Re: Banebots RS-775 Case Short
 

Just as long as paying more doesn't involve $30 tetrix motors that are even worse...

Re: Banebots RS-775 Case Short
 

Well, we paid $5000+++ to enter a competition that limits us on what we use to certain items. I'd prefer it if those items weren't faulty. Just sayin'

Re: Banebots RS-775 Case Short
 

I agree... I'm not defending FIRST. I'm pointing out reality (as I see it).

I've been doing this for 17 years now... FIRST has always limited "the brand/model and number of motors" and I see absolutely nothing in the tea leaves predicting a change.;

Re: Banebots RS-775 Case Short
 

And in my opinion, you paid about $4000 too much...

Re: Banebots RS-775 Case Short
 

Just a warning...

Both RS-775 motors that we used on our competition bot that had been "fixed" by zapping became "unfixed" by the end of the first day of qualification rounds - the case shorts returned.

Re: Banebots RS-775 Case Short
 

Is that what was disabling daisy?

Re: Banebots RS-775 Case Short
 

The jury is still out - we pulled off anything we suspected before crating and will be doing CSI-style forensics in the coming days and weeks to get this fixed in time for Philly...

Re: Banebots RS-775 Case Short
 

Not related to a case short, but some of our 775 gearboxes for our arm motors were starting to tear up at Florida. The casing on it would start to rotate around the gears and this was tearing the inner gears up, has anyone else had this problem or had a solution to it?

We tried using hose clamps, but they only stop it from rotating so far.

The black pins that hold it from rotating would just pull out or shear off.

Re: Banebots RS-775 Case Short
 

Jared,

I would not be surprised if the RS-775 case shorts were causing your robot to die. We have had an endless stream of issues arising from these motors. Every single motor we have ordered from Banebots has come with or developed a case short. (Some of the motors were not tested until we had already used them. It's not our standard operating practice to test motors for case shorts prior to usage. We've now adapted our procedures to assume manufacturing incompetence.) Just in Pittsburgh alone these motors led to multiple trips of our main circuit breaker, trips of the motor breaker and possibly a fried cRIO. (The cRIO is definitely fried, but we're not 100% sure it's the fault of the Banebots. Although I have no idea why we're giving them the benefit of the doubt at this point.)

I highly recommend that any team who experiences weird issues with their robot to check the resistance from the leads to the case of their Banebot motors. Please spread the word to teams who don't read Chief. We saw a lot of teams in Pittsburgh who were having issues, and had no idea it could be traced back to a case short.

Re: Banebots RS-775 Case Short
 

Warning seconded...we spent 3 days dealing with case short gremlins...days we could have used programming a two tube auto!

Re: Banebots RS-775 Case Short
 

Karthik,

Thanks for the reply. Unfortunately, short of vigilantly changing out the RS-775s every time we detect a case short, I'm not sure what our best course of action is right now. We can drop from 6 drive motors to 4, but the roller claw absolutely requires an RS-775. Maybe non-metallic mounting hardware could at least help reduce the risk of a case short electrifying the entire frame.

Re: Banebots RS-775 Case Short
 

We are also finding that the case short on our 775's come back after some practice on our practice bot. We will be checking the case on the 775's after every match as part of our after match system check.

We have also found that when this happens, the two banner sensors we have very close to these motors also exhibit the flashing green light occasionally which according to the manufacturer is output overload. This causes us to lose some counts on our lift. If we move our lift by hand, no Banner issues. If the cases aren't shorted, no Banner issues.

So, if you are using the 775's and are experiencing some funny signals from sensors, this could be a suspect. Just FYI...

Unfortunately, we have no way to isolate ours from the frame...unless someone has an idea for non-conductive bolts (other than plastic)...