Bad motor? Can you identify the problem? (Photo)

[photojunky]

These are photos of the motor that was failing. When I run it, it tries to rotate but only moves in quarter inch increments for a couple of moments. Can anybody identify the issues from this photo? Looks like some stray windings but they did not appear to be hitting anything. Would they cause a short? Not sure about the other side. Could it be arcing?

 

[DrAbsurd]

Maybe something got on it and then melted into it. Not sure, cause it does look like arcing.

 

[Gyro Doctor]

... That's what is generally called one fried motor ... lol ... technically, it lost a phase.
Quad motors are three phased outrunners. Each phase has coils at 180 degrees opposite each other
which, when energised, make the north and south poles of an electromagnet. The carnage you see is one phase
that fried, hence baking the coils in diametric opposition. The general darkening of the coils indicates it overheated
the insulative coating, after which point that fails and arcing occurs which pretty much just trashes the copper wire,
which are the areas that look melted. The ESC associated with that motor should also be considered suspect too.
If not for causing the failure then likely it became stressed it's self due to the failure.

 

[Rick M]

... That's what is generally called one fried motor ... lol ... technically, it lost a phase.
Quad motors are three phased outrunners. Each phase has coils at 180 degrees opposite each other
which, when energised, make the north and south poles of an electromagnet. The carnage you see is one phase
that fried, hence baking the coils in diametric opposition. The general darkening of the coils indicates it overheated
the insulative coating, after which point that fails and arcing occurs which pretty much just trashes the copper wire,
which are the areas that look melted. The ESC associated with that motor should also be considered suspect too.
If not for causing the failure then likely it became stressed it's self due to the failure.

It's good to have an expert or two in the mix.

 

[Gyro Doctor]

... That exact same thing happens to 600V 100HP industrial motors too.

 

[mozquito1]

The wires are coated in a non conductive coating. Hence the reason they run in water. If that coating has gone then yep it will arc & be erratic. Unless you got the right wire & can wind a motor, you need a new one. Keep the bell & clips as spares.

 

[BL Swagger]

On the topic of motors... I clipped a branch the other day and the motor top/cap with the propeller popped off. I continued to just put it in back in and the magnetic force was pretty strong pulling it back to place. It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?

 

[mozquito1]

Replace the bell. A hard manoeuvr will make it come off.

 

[mozquito1]

I don't mean snap your banjo.

 

[Jackson]

It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?

Sounds like you threw a c-clip, it's on the bottom and fits into a slot of the shaft. Although some newer designs use a shaft screw.

 

[BL Swagger]

Sounds like you threw a c-clip, it's on the bottom and fits into a slot of the shaft. Although some newer designs use a shaft screw.

Yes, the same thing happened again, just now, when going around the same tree haha. On closer inspection, I could see the c-clip holding it in was missing. Flies just fine without the clip, but definitely a vulnerability.

 

[photojunky]

Yes, the same thing happened again, just now, when going around the same tree haha. On closer inspection, I could see the c-clip holding it in was missing. Flies just fine without the clip, but definitely a vulnerability.

Do not fly without the clip. It will only end in disaster but I'm sure you know that. The only thing holding it in place is the magnetic force.

 

[GJH105775]

These are photos of the motor that was failing. When I run it, it tries to rotate but only moves in quarter inch increments for a couple of moments. Can anybody identify the issues from this photo? Looks like some stray windings but they did not appear to be hitting anything. Would they cause a short? Not sure about the other side. Could it be arcing? View attachment 4107 View attachment 4108 View attachment 4109

Are there any marks caused by a screw indenting the coil? Could have shorted through the bell across to the other coil on that same phase.

On the topic of motors... I clipped a branch the other day and the motor top/cap with the propeller popped off. I continued to just put it in back in and the magnetic force was pretty strong pulling it back to place. It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?

While the magnetic force is usually enough to hold it in place if you were to punch out and then cut throttle the magnetic force would not be too strong, while the prop pulls on the motor with about the same force. This causes a cool looking take away prop, and a not so fun crash. Usually, the quadcopter hits the ground before the prop which looks pretty interesting.

 

[Dugdog47]

Okay since I've had to learn about these motors lately, what's the popular opinion about the "c clip" versus "set screw" retention on the brushless motors. I E, which is better?

 

[Rick M]

Okay since I've had to learn about these motors lately, what's the popular opinion about the "c clip" versus "set screw" retention on the brushless motors. I E, which is better?

I've no experience with the set screw types, but given my experience with c clips, ANYTHING would have to be better. They work great, until they don't...then they come off.

ETA: I'm assuming you would want a tiny drip on blue Loc-Tite on the set screw.

 

[mozquito1]

Screw, but still loctite them. I've bent loads of them clips or lost em when they ping off. Before today I have solderd where the clip should be.
It could have been a small stone done the damage, then broke up & spatt out.
I think if it was a screw, the damage would be full circle on the windings.

 

[mozquito1]

WTF is going on under there, someone left an extension lead in it. That looks like the work of a screw but the top one doesn't. That's a big arsed motor.

 

[photojunky]

View attachment 4117
WTF is going on under there, someone left an extension lead in it. That looks like the work of a screw but the top one doesn't.

it could be, but if that was from a screw, wouldn't there be some scratches from the friction which I cannot find. Could it have just been sloppy craftsmanship from the factory?

 

[mozquito1]

Looks like a stone on top but all that loose wire underneath maybe a screw.
If it was a screw on top, there's would be marks the whole way round.

 

[photojunky]

Looks like a stone on top but all that loose wire underneath maybe a screw.

Well, I have crashed into a pile of dirt twice