Shooter burning motors...but why?

[FrankJ]

Measure the current to the motor. Knowing the current & voltage going to the motor & the motor curve you can get a good guess of speed. Free running at anything more the %70 of stall torque amps is cause for concern.

Maybe you have too much compression on the ball? When the ball hits the shooter does it stall the motor & it is inertia loading that is killing the motor?

The FP are pretty durable. They take a lot of abuse. Holding them full power at stall for any length of time would be abusive.

If you run thru the PD board, the CB will give you a little protection from burning up the motor.

[Ether]

Originally Posted by FrankJ

running at anything more the %70 of stall torque amps is cause for concern.

Running at anything more than 50% of stall torque amps is a cause for concern. Or possibly even less.

[matthewdenny]

Could anyone point me in the direction to find the motor specs documentation? A link would be great.

[Sefunx]

We found, (through a burned hand), that all motors will get hot, so its a good idea to have a Spike or use a speed controller to, overall, turn off motors when they don't need to be used.

[EOC]

We burned up a 550 shooter motor and found the cause to be a bad bearing.

[MrForbes]

motor info

http://www.usfirst.org/sites/default...torInfo4.1.pdf

[FrankJ]

Running at anything more than 50% of stall torque amps is a cause for concern. Or possibly even less.

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

[Jimmy Nichols]

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.

[matthewdenny]

Originally Posted by Jimmy Nichols

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.

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

[protoserge]

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.

[artdutra04]

Originally Posted by stinglikeabee

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.

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.

[protoserge]

Originally Posted by artdutra04

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.

This is true. Thanks for the addition

[drwisley]

Originally Posted by artdutra04

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.

Or an isolated coupling.

[J.Warsoff]

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.

[Ether]

Originally Posted by Aerosound

They would get hot very fast due to frequent running at high speeds.

High speeds is not the problem. High loads is.