Re: Shooter burning motors...but why?
 

or here:

http://www.chiefdelphi.com/media/papers/2432

Re: Shooter burning motors...but why?
 

You are right. I was actually thinking of 30% stall torque amps which would be about 70% free speed.

Re: Shooter burning motors...but why?
 

We burned up a couple because we blocked the air vents. Good ole CD search turned that one up quick. We are mounting our motors in the sideplate of our shooter, a couple holes in the sideplate inline with the vents and problem solved.

At least the banebots aren't as much as the tetrix motors from last year.

Re: Shooter burning motors...but why?
 

Turns out we were covering he vents. Works great now. Thanks everyone.

Re: Shooter burning motors...but why?
 

If you have time to pick up some hobby motor heat sinks from towerhobbies.com, there are black ones that fit the 550 series diameter perfectly. I think we had to cut them to fit. http://www3.towerhobbies.com/cgi-bin...&I=LXNAB1&P=ML

Pretty much all failures with BaneBot motors are attributable to excessive heat buildup. I am working on an FRC MTBF plots for the BaneBots using our motors, understanding there are various uses and setups. If I have time, I'd like to put a call for data from the community.

Another thing to watch out for is case shorts. Once the motors heat up too much, the enamel used for sealing the shaft melts off and then the current is allowed to flow from each terminal to the case of the motor (and then your robot). Make sure you consider mounting with nylon screws and washers or other non-conductive hardware. Please note that a case short does not indicate the motor is gone. We've run case short motors for a reasonably long duration before they finally failed.

Re: Shooter burning motors...but why?
 

Plastic mounting screws are only half the battle to having a fully electrically-isolated motor. You also have to isolate the motor output shaft via either plastic gears or timing belts.

Re: Shooter burning motors...but why?
 

This is true. Thanks for the addition :)

Re: Shooter burning motors...but why?
 

Or an isolated coupling.

Re: Shooter burning motors...but why?
 

We lost one of the RS-550 motors on our shooter, too. We have two driving a single shaft, and one of them started making funny buzzing noises. Upon close examination, we found that the plastic fan had become detached from the motor shaft, and was not providing full cooling. We don't know if this was the root cause of the overheating, or a symptom.

I should note that this was after several hours of intermittent running, calibrating the shooter speed to distance from basket, for our vision based shooter control. We replaced the motor, and placed a couple victor fans so they blow continuously over the exterior of the motor cases. Our motors stay cool now. Got to love forced convection.

Re: Shooter burning motors...but why?
 

Yes, the root cause is overheating. I assume you are using a cimulator. If so, you should mill the face of the mounts down to allow air to flow into the motor intakes.

A good idea is here:
http://www.chiefdelphi.com/forums/sh...d.php?t=101996

Re: Shooter burning motors...but why?
 

We had a similar problem with our BaneBots for the shooter. They would get hot very fast due to frequent running at high speeds. I came up with a solution using fans. I found a box full the small fans that they use on the Victors and only had to use 2 of them. I extended to the wires to they could reach down from the top of the robot where the shooter is to where the electrical board. Since the fans on their own count as electrical loads, I had to wire them to Spikes wired to the PDB. As for mounting the fans, all I did was use velcro strips (looped strip on side of fan, hooked strip under the motor) to keep the fans in a position where they blow up and against the side of the motors.

THe fans have worked wonders for the motors. They will either stay relatively cool during extended use, or will cool in under a minute after heating up. Weight was no issue at all, being that both fans and Spikes, along with the wires, weighed in at only 0.4 lbs in total.

This may be a good solution to overheating motors. I'll put some pictures up soon as a reference.

Re: Shooter burning motors...but why?
 

High speeds is not the problem. High loads is.

Re: Shooter burning motors...but why?
 

I stand corrected. The load and the gear ratio combined can also cause problems, I believe.