Always hand spin your motors before take-off.

[Jtrjr]

Okay, I've got a start here. Totally unscientific. Just going with my gut and years of experience building and working on my scoots. I'm totally out of my league here. As we all know, I had a single motor that appeared to have more resistance than the other three motors. I chose to pull the motors and administer a single, minute drop of oil on the shaft of the motors (around the sealed bearings), top and bottom. I cleaned all residual oil off and ran low pressure air to all of the motors, both top and bottom. I worked the oil in, reassembled the bird and spun up the motors. All seemed very good. No more resistance.

At the advice and concern of others that the oil may have an adverse effect on things, I pulled everything apart today, inspected everything thoroughly and put it all back together again. I found no signs of residual oil or spillage on any plastic parts.

I will provide an amateur video of what it sounds like now (I wish I had done one when the problem first surfaced but I didn't). I will use the "feel" from hand, spinning the motors and the sound of this video as a baseline. If my fix works, great. If it doesn't, I'll share the results and everyone will know better. I've got no dog in this fight, I'm just trying to keep my birds in the air in a safe and responsible manner. We'll see what happens.

Jerry

 

[Reed L]

Which motor was bad? rf? rr?, etc...

 

[Jtrjr]

Which motor was bad? rf? rr?, etc...

Reed,

Not trying to be a smart@*** but you tell me? Do you hear or see any difference? I really wish I had done the before and after. Before I give up what motor it was, let's see how the bird performs. Let's see if it starts to show itself. I really want to learn from this experience. Maybe some of the others can determine what motor it was. At the end of the day, I'll be completely honest. I'm not like some here, I don't know much but I'm also unwilling to take the word of just anybody with a bird and internet access. I've got to learn the hard way, by experience. I'm by no means the brightest bulb on the block but I'm not the dimmest either. I can't wait to do some serious flying!

Respectfully,

Jerry

 

[Reed L]

When your camera came off of the front left, the pitch changed lower, not sure if it was left and right side or if you didn't take it up as high but it was easily distinguished from the front to back. I initially thought that it was front right but then after listening again, it's as you came away from the left front, but both sound different or lower then the back, hehe...

 

[Jtrjr]

All,

Getting prepped to run the Big Sioux River Run (again) on the oiled P3 motors. Weather is a bit iffy but if I get a good sat lock, I'll go. It'll be a good test of the "oiled" motors. The run is about 6 miles in total, home point max distance will be about 2.5 miles. Let's see what this baby does! Just waiting on the battery right now.

Jerry

 

[Jtrjr]

Battery is flashing four bars, light is starting to go down. If I can get the bird in the air in next 15-20 minutes and can get a solid sat lock (it's really overcast today) I should be good to go. If she makes it, it's all good. If she doesn't, I should have heeded the many warnings.

Jerry

 

[alokbhargava]

Keep going, keep experimenting, thats the fun of life.

 

[Reed L]

Battery is flashing four bars, light is starting to go down. If I can get the bird in the air in next 15-20 minutes and can get a solid sat lock (it's really overcast today) I should be good to go. If she makes it, it's all good. If she doesn't, I should have heeded the many warnings.

Jerry

Sat Lock? We don't need no stinking Sat Lock, hehe I must say that the one time that I did crash was because there were no Sat' s at all under the Redwood Tree' s Canopy, but I use course lock now and it's a lot better flying and knowing that when I pull back on the right stick, no matter which way it's facing, that it comes back to me when there's no sat connection available.

 

[Jtrjr]

Keep going, keep experimenting, thats the fun of life.

Got the run done. All went very well. Upon landing checked each motor. None hotter than the other. All actually quite cool. All spun equally by hand. 52F degrees and some pretty good gusts but she ran great! I'll post the screen record soon. I don't have time for a full edit. I'll take her down to the shop in the morning, open her up again and carefully inspect everything but so far, so good.

Jerry

 

[Jtrjr]

Just a simple screen record from today's flight. Weather sucks here. I don't think I'll be getting a lot of flying time but when opportunity strikes I'll be on it. Everything went as planned and the bird seems solid. Time will tell.

Jerry

 

[flyNfrank]

Preventative maintenance, or not, there is something about the P3 that needs to be known. The P3 functions under a pretty decent propulsion system. The algorithm in the ESCs have been tuned and customized specifically for the P3. Should there be a minor issue with in one of the four motors. the propulsion system will adjust the other 3 and compensate for the irregular performance.

The #1 problem to take place is on the bottom of the motor. A snap ring on the shaft slips from it's groove near the end of the shaft. This creates play and side to side movement to point that some contact damage may take place and major motor failure could be the result. There is a change in sound pitch that gets worse the longer things take place. If found in time there is a possibility of putting things back together with no issues.

If you are in fact trying to improve performance, keep in mind to work with substances that are tolerant to heat. Otherwise the heat from the motors will simply sling off whatever used during acceleration.

 

[Jtrjr]

Went down to the shop this morning and went through everything again. All looks solid. All motors seem to be equal. I can no longer "feel" any resistance on the suspect motor. They all "feel" just like the ones on my newer bird. No dirt or dust accumulation when looking with a magnifying glass. So far, so good. The four new motors have arrived in the event that I feel it necessary to replace the suspect motor.

Jerry

 

[Erised]

By oiling these sealed bearings you only lubricated the seals. Since you noticed a reduction in friction after oiling means that a lack of lubrication in the bearing is present. A proper amount of lub in the bearing will wick between the seal and inner race and reduce friction. Having had this increased friction could mean a lack of lub, thus increasing friction and heat witch cooks the seal. The damage to the seal is permanent. Lubrication of the seal is very short term because the bearing now lacks the proper amount of lub and will eventually fail. Furthermore when pressing a bearing on a shaft or in a housing it is imperative not to pass the pressing load threw the balls of the bearing as they will indent in the races. If you press a bearing on a shaft you must press on the inner race NOT the outer race. If you are pressing a bearing on a shaft and a housing at the same time you must press both the inner and outer race at the same time to prevent putting any static load on the balls onto the races.

 

[Jtrjr]

By oiling these sealed bearings you only lubricated the seals.

Erised,

I think it's necessary to explain a little bit about who I am. I'm not an expert at anything, I'm a half of jack at all trades at best. I'm "John Doe". I encounter a problem and I do whatever I can think of to solve it. I read a lot and I learn as much as I can. I'm the guy that had my brakes go out in my '73 Dodge Dart and used the emergency brake for a month to get around. My primary belt on my motorcycle split off going down the backside of Big Bear and I used my pants belt and one from one of my friends to limp the bike down the mountain.

I know I'm tempting fate with this thing but so be it. I have 4 brand new motors sitting here right now. I've learned a great deal from this thread but I'm not giving up just yet. When the time is right, I'll quit and I'll let everyone know that I was wrong but for now all "seems" good. As I said, time will tell. I think I used a tiny bit of a premium oil that will help, not hurt this bird but I've been wrong many times before in my life and this could be another one. We'll just play it out and see what happens! No skin off of anyone's back but my own.

Jerry

 

[Oso]

I have always done this but it seems many don't. You need to "feel" the resistance in your motors. If you don't, you're never going to know if something is going amiss.

Thanks for this post Jerry. I have never done this with any consistency such as in a pre-flight checklist, but I will try to do it more now that you have highlighted it.

 

[Erised]

If you oil seals from the outside it may cause other problems besides accumulating dust. Oils are not always compatible, mostly cause by their additives and the type of base the grease in the bearing has. Often non compatible lubrication will have a chemical reaction that will cause premature breakdown of the lubrication properties. As minute is the area under the seals lip this will eventually destroy the capacity of the seal to do it's job of keeping the grease in and the dirt out. This may or may not happen because we don't know (in this case) how the different lubricant will react with each other. Good seals don't need any external lubrication and they attract dust witch then goes and sticks to the motor windings and trap more heat. Always a good idea to check the motors before you fly..good job!

 

[Jtrjr]

When your camera came off of the front left, the pitch changed lower, not sure if it was left and right side or if you didn't take it up as high but it was easily distinguished from the front to back. I initially thought that it was front right but then after listening again, it's as you came away from the left front, but both sound different or lower then the back, hehe...

Reed,

It's the front left looking from the back of the bird but you already knew that. We'll see how she holds up.

Jerry

 

[Mako79]

I have always done this but it seems many don't. You need to "feel" the resistance in your motors. If you don't, you're never going to know if something is going amiss. Yesterday, I did this and one motor didn't "feel" right. It had more resistance that the other three. I took my air compressor, turned it down to 30psi and blew some air through the motor (making sure my compressor was clear of any water). It was still not right. It still had a bit more resistance than the other three. I took it down to the shop to look at it further. It was clearly different.

I ordered up a few more motors and decided to look a little deeper. These are sealed bearings, right? They don't need any oil, right? Having worked on motorcycles my whole life, that's what it "felt" like to me, like it needed oil. I have some Tri-Flow "Superior Lubricant" oil here for other stuff. Super lightweight. I decide to try it. It has a tiny nozzle, almost like a syringe on it. I put a drop on the top bearing, pull the motor from the arm and put "a drop" on the bottom bearing. I turn the motor back and forth, over and over again. It seems like its working. I decide to do the same to the other three motors. It all looks good. I give it a bit of time to seep in and keep hand spinning the motors. First sitting on the landing gear and then turning it upside-down.

I hook up the RC to the bird and power her up (no props) and spin the motors for a while. Let her sit again for a bit. Now the motors all feel close to the same. I push a bit more air (low pressure) through both the top and the bottom of the motors just to spread it around and get the residual out and all is good. Motors feel consistent and she flies like a dream! Sealed bearings or not, it had a big impact.

Am I telling you to do this? Hell, no! I'm telling you that it worked for me (so far). I'm just sharing my personal experience.

Just really get to know your bird.

Jerry

You blowing all the dirt out resolved half your issue me thinks.

Do me a favour and inspect the outer bell housing of the motor. Use a magnifying glass and look for tiny foreign black ferrite in the gaps of the silver neodymium magnets. When the black ferrites touch, it bridges the magnets and changes its phase/polarity. If enough if this bridging happens, the motor will have resistance as there will be a phase that is more bias. A symptom is that the motor will make a squeal at certain rpms (usually lower rpms). Due to the strength of the magnets, the ferrite is difficult to remove with an air blower. There are techniques to remove without having to pull apart the Phantom or motor.

To avoid this, try not to tip over on landing or get dust/sand in your motor when landing.

 

[Jtrjr]

Do me a favour and inspect the outer bell housing of the motor.

Mako,

Thanks, will do!

Jerry

 

[bernek]

After investigating a bit and talking with Marknmd I've got to the conclusion that bearings don't need any kind of lubrication. If they need lubrication then the damage has already been done and oil is just masking the problem. They will fail eventually if they show any kind of "unfamiliar" resistance. I recommend changing the bearings instead of lubricating them because it will attract dust and cause even more problems - also the arms will get messy since the oil will be thrown everywhere when spinning at high RPM.

The bearings are not oiled from factory they are greased and the special grease is applied "for life" if it disappears somehow then the bearing is already compromised and no longer "sealed".

Also if you did oil a bearing that is greased and sealed lets assume the oil gents inside then it will wash away the grease and the bearing has to be oiled regularly or it will fail sooner than without oil.

I would say changed them than oil them before every flight.