One motor feels "notchy"

[mroberts]

I've racked up somewhere between 90 and 120 minutes of flight time on the Phantom, and one of the motors now feels a bit wierd. It doesn't rotate as smoothly as the others and feels sort of "notchy" - it almost feels liek it "clicks" into place at about 12 locations around it. One the other ones I can feel a little bit of resistance as they go around, but this one does it to a much greater degree.

The linked video shows that as I turn it, it will actually jump to the next position, and it does it so solidly that the whole phantom moves!

Video

Any ideas?

 

[Ali in Austria]

Just had the same on one of mine. Replaced the bearings and oiled all 4 motors. Much, much better.

 

[mroberts]

Hmm. Got this reply on another board:

"That's commonly called 'cogging'. It's nothing more (or less) than the stator core arms being attracted to the magnets on the outside. It indicates NOTHING about performance....repeat, nothing. Some people seem to think it does. Some motors have it to a high degree, others show little cogging.

Why does one do it and another does not in seemingly identical motors? Cheap motors with no QA at all. The reality is if carefully tested you'd find more than cogging variation in those motors. If it flies OK, don't worry about it. You'd spend more getting quality motors than the entire unit cost you. "

Dispersions on quality aside, anyone want to weigh in on a tie-breaker - replace bearings vs. do nothing?

 

[Gizmo3000]

well, replacing and oiling the bearings is pretty minimal and can't hurt.

But my indication of something being wrong is when there's an actual noise and/or the motor gets hot

 

[Roadkilt]

Your comment on oiling bearings is interesting. My feeling is to not do anything unless needed. Bearing oil is a dust magnet and with each landing is going to attract that kicked up dirt. Then you are stuck really maintaining those bearings.