[size=14.6667px]I noticed a copper "dust" on the two silver rotors/props on my P4 yesterday (See picture). There is no dust on my black rotors/props. Something is getting shaved or worn, but what? And why only the silver and not the black?
[size=14.6667px]Any help would be greatly appreciated!
[size=14.6667px]God Bless,
[size=14.6667px]Bill

You need a spring around the shaft of the engine. Try and compare with the other engines. Think you can buy the prop holder that is screwed on the engine together with the spring.

You should not fly before it gets changed as you risk losing a prop in the air. Then there's only one way if it happens ....................... and it's down.   

Regards Leif.

Landbo Posted at 2018-6-2 08:23
You need a spring around the shaft of the engine. Try and compare with the other engines. Think you can buy the prop holder that is screwed on the engine together with the spring.

You should not fly before it gets changed as you risk losing a prop in the air. Then there's only one way if it happens ....................... and it's down.   

He shouldn't need new prop mounting plates, those are the leaf spring variety as provided on the P4.

They shouldn't be a problem.

It wouldn't be the result of surface corrosion on the centre spindle. Why only the silver props, perhaps different manufacturer for CW & CCW motors ?
Other than that I can't think of what might cause this.

Aardvark Posted at 2018-6-2 08:41
He shouldn't need new prop mounting plates, those are the leaf spring variety as provided on the P4.

They shouldn't be a problem.

Thank you, those words I could not find in English, "prop mounting plates". On reflection, should the man probably also have a set of new props. Highly recommend a set of new low noise props.   

Regards Leif.

Think about it. One pushes the air up the other pushes the air down.

Grumpy D Posted at 2018-6-2 13:07
Think about it. One pushes the air up the other pushes the air down.

No, the props may run in the opposite direction, but they both provide lift, they don't push air up.

Aardvark Posted at 2018-6-2 08:44
It wouldn't be the result of surface corrosion on the centre spindle. Why only the silver props, perhaps different manufacturer for CW & CCW motors ?
Other than that I can't think of what might cause this.

I thought the motors were identical just one set wired in reverse polarity.

But most likely reason is the prop centre hole that fits over the shaft is wearing out posibly caused by vibration.
Have you tried a different set of props?

I have this too on my p4p...... not sure which motor though, i wasnt overly bothered, deffo rust dust oh and it was there prior to the ditching

Grumpy D Posted at 2018-6-2 13:07
Think about it. One pushes the air up the other pushes the air down.

You are correct. Note to self: Don’t Post after Happy Hour.

Grumpy D Posted at 2018-6-2 23:09
You are correct. Note to self: Don’t Post after Happy Hour.

the really funny part of that comment was right at the beginning "Think about it" ... almost fell out of my chair laughing.

It's basic aerodynamics but often misunderstood. Props are wings basically. Lift is produced by producing a negative pressure differential above the wing (with some positive pressure produced below the wing). The negative pressure above the wing (or prop) basically "lifts" the aircraft upwards. And of course we all know that the black props spin in the opposite direction of the silver props in order to keep the quad itself from spinning. Helicopters employ a tail rotor to accomplish the same thing but explaining that would be more complicated.

I would assume they are ball bearing race motors, not bushed?, mmmm....never had one apart to inspect.

Yes.  They are brushless motors.   There’s no polarity, the esc controls motor direction.  On racing quads you can actually access the ESC programming and reverse motor direction without even heating up the soldering iron.
As for the strange “copper dust” I’m curious how many hours are on these motors and props?  Might be time to simply replace them if they’re high hours.

Are you sure it is copper? The only copper source I can think of is the coils in the motors' stators... BTW, to test if it really is copper, you could try this simple test:    and use a clean cotton swab to collect the powder from the propellers.

Antonio76 Posted at 2018-6-3 03:55
Are you sure it is copper? The only copper source I can think of is the coils in the motors' stators... BTW, to test if it really is copper, you could try this simple test:  https://www.youtube.com/watch?v=k9_zpXosCPA

More likely rust, and you've packed the drone away damp at one time. Should really strip the motors to find what is corroding. If it were mine I would apply a little ACF50 (anti-corrosive agent, harmless to electronics) to the affected area.

There are approximately 50 hours on the props. The "copper dust" was my description, an untrained eye observation and not necessarily a statement of fact. I've read the thread and the debates within and I'm not sure what is being recommended. Anyone who has posted-Do you have bench experience with DJI drones?  Can someone elaborate as to what ACF50 is and the most effective way to use it?
I live along the coast. With that said, the P4 is kept inside and flown only in optimal conditions. The dust appears to be rust, but I spent 30 years in TV/Film production and never had a rust problem before.
Thank you for your input!
God Bless,
Bill

Bill Hitchcock Posted at 2018-6-3 07:04
There are approximately 50 hours on the props. The "copper dust" was my description, an untrained eye observation and not necessarily a statement of fact. I've read the thread and the debates within and I'm not sure what is being recommended. Anyone who has posted-Do you have bench experience with DJI drones?  Can someone elaborate as to what ACF50 is and the most effective way to use it?
I live along the coast. With that said, the P4 is kept inside and flown only in optimal conditions. The dust appears to be rust, but I spent 30 years in TV/Film production and never had a rust problem before.
Thank you for your input!

For ACF50 check Amazon: https://www.amazon.com/ACF-50-An ... L70_&dpSrc=srch

But don't just spray it on everything, a little goes a long way and you really want to know what it is that has corroded. In my experience ACF50 is extremely effective for killing and preventing rust, and it's also an OK lubricant (but there are better, more specific, products you should use as a lubricant). It is also very effective for keeping water out of electrics and preventing shorts. Do not get it anywhere on your glass camera lenses - it's a devil to wipe off - the very property that makes it so effective as an anti-corrosive. It won't actually damage the lens but you can't simply wipe it off with a tissue. Can't offer more advice without knowing what is rusting away! Something may need replacing..

Bill Hitchcock Posted at 2018-6-3 07:04
There are approximately 50 hours on the props. The "copper dust" was my description, an untrained eye observation and not necessarily a statement of fact. I've read the thread and the debates within and I'm not sure what is being recommended. Anyone who has posted-Do you have bench experience with DJI drones?  Can someone elaborate as to what ACF50 is and the most effective way to use it?
I live along the coast. With that said, the P4 is kept inside and flown only in optimal conditions. The dust appears to be rust, but I spent 30 years in TV/Film production and never had a rust problem before.
Thank you for your input!

My springs are also a little rusty but that does not matter. If it were me who owns your drone, I would not lubricate / spray anything on your prop mounting plates. This because I do not know if the chemicals dissolve or make the plastic crisp over time. If that happens and the disc breaks when you fly, there is only one way it can go and that's down.  ;-)

Regards Leif.

Hi, sorry for the inconvenience, please try to wipe clean it and check the performance, if there is any further issue, please feel free to let us know, thanks.

ChrisLX200 Posted at 2018-6-3 07:59
For ACF50 check Amazon: https://www.amazon.com/ACF-50-Anti-Corrosion-Lubricant-Compound-Aerosol/dp/B000P1C8UO/ref=sr_1_2?ie=UTF8&qid=1528041163&sr=8-2&keywords=ACF50&dpID=41%252BcIFpc4TL&preST=_SY445_QL70_&dpSrc=srch

But don't just spray it on everything, a little goes a long way and you really want to know what it is that has corroded. In my experience ACF50 is extremely effective for killing and preventing rust, and it's also an OK lubricant (but there are better, more specific, products you should use as a lubricant). It is also very effective for keeping water out of electrics and preventing shorts. Do not get it anywhere on your glass camera lenses - it's a devil to wipe off - the very property that makes it so effective as an anti-corrosive. It won't actually damage the lens but you can't simply wipe it off with a tissue. Can't offer more advice without knowing what is rusting away! Something may need replacing..

Just read this on one of the reviews

I have also more recently read a military test report on acf50 effect on electronics, where once thought to be effective now says under certain circumstances it can cause problems with connectors, so I have reframed from applying it to electrical connections just to be safe.

I wouldn’t use lube on DJI motors.  They are sealed bearing motors and shouldn’t need it.  To the OP, I doubt what you see is any problem.  As long as the motors still feel smooth, and aren’t acting more or unusually noisy they are likely just fine.  You can almost always tell if a motor is failing by how hot it is after landing.  It’s normal for phantom motors to be pretty warm to the touch, as in “wow that feels pretty warm!”   However if one is, “Ouch, I can’t hold my hand on that for very long!” That’s too hot and you probably should replace it.   Obviously this is very basic advice, but it works.  You’re looking for one motor that is significantly hotter than all the rest.

My P4P, both the original and a replacement are leaving the same brown stuff in the props, have not been able to see any rust but it only can come from the hub pin, spring or washer as nothing would be blown up in the props hole from further down. I think it is some kind of grease/oil added for protection that is getting brown and color the props.
I see it on both the black and white dotted, more on some than other, have not found any reason to worry as long as everything seem to fit tight.

Bill Hitchcock Posted at 2018-6-3 07:04
There are approximately 50 hours on the props. The "copper dust" was my description, an untrained eye observation and not necessarily a statement of fact. I've read the thread and the debates within and I'm not sure what is being recommended. Anyone who has posted-Do you have bench experience with DJI drones?  Can someone elaborate as to what ACF50 is and the most effective way to use it?
I live along the coast. With that said, the P4 is kept inside and flown only in optimal conditions. The dust appears to be rust, but I spent 30 years in TV/Film production and never had a rust problem before.
Thank you for your input!

The shaft rotates with the motor, as does the propeller, so there should be almost zero wear between the shaft and prop.  It is hard to explain why the hole in the prop is looking so dirty.

The shaft is only for locating the prop in the correct location, a little surface rust is not a problem.

My suggestion is that you clean the shaft, maybe with a cloth holding a very small amount of WD40 or similar, it may then become more obvious what the issue is and if it is rust then it will help prevent further rusting and possibly the prop getting stuck on the shaft.  Don't use lubricates on anything else in the motor, they could possibly weaken the plastics and you don't want to wash the existing correct lubricant out of the motor bearings. You can wash the prop with dishwashing liquid.

Some people would replace the props when they have 50 hours use rather than clean them, would be a good excuse to fit the new quiet 9455S props.

My guess is that it has been stored either damp or with the shaft sitting on something damp, and since you are near the sea maybe it had a bit of salt on the surface of the shaft.  Why only on the two props I don't know but they are likely to be from different batches because of the different rotation directions, maybe the surface treatment was better on one pair.  

Maybe in future store it in it's box with a bag of silica gel to keep moisture under control.

KedDK Posted at 2018-6-4 00:37
My P4P, both the original and a replacement are leaving the same brown stuff in the props, have not been able to see any rust but it only can come from the hub pin, spring or washer as nothing would be blown up in the props hole from further down. I think it is some kind of grease/oil added for protection that is getting brown and color the props.
I see it on both the black and white dotted, more on some than other, have not found any reason to worry as long as everything seem to fit tight.

Not sure if it is rust, as you say it may be a lube or protectorate of some type.  I am a FFL (Federal Firearm Licensed) and can tell you I have see this on numerous firearms from the manufactures and thought it was rust.  I contacted them and it is a grease/lubricant to prevent corrosion.  It looks  just like rust.
Just my opinion.  

I looked at mine and 3 out of 4 have the coloured stuff,  i wonder what DJI's take on this is?