I seem to remember a discussion about the need to oil the motor bearings every 6th flight.
OMG!
I was on the phone with 3DR about another subject and when finished I said "oh by the way"
blah, blah, need to Lube? and the answer was yes, I will send you the directions.
I did not receive the information as of 2 weeks later.
How often to do oil the bearings?
with what oil?
and how?
Decades ago I built anemometers for a research project and calibrated them in a wind tunnel. I found that
it was better to run the bearings dry as it did not collect dirt as well. The bearings were very lightly loaded
so it seemed to work. It seems to me that when I fly and apply vigorous attitude adjustments the bearings are sufficiently loaded to require Lubrication.
Can I get a witness?
How about, how often and the technique.
Safe landings
Dan
Replies
I'think that recomendation It's the minimun time that a good bearing can fly without fails, my cheap chinese ones, perhaps have more than that, but it's an alert that You have to do something else than only flies If you don't want to have surprises, then, any case it's different, if you only fly by hobby, a cheap ship near you is something, and if you fly for work with an expensive cameras, or flying away you, it's another risk. I think too that if Iris didn't especificate nothing about bearings they are cheap chinese too, good quality bearings are especificated by manufacturers in general. I think so that every 6 flyes don't have sense, but only my opinion.
I'm probably going to open mine up soon to give a good cleaning. I'm thinking to stop using the INOX lub I've been using.
I'm using these: http://www.multirotorgear.com/t-motor-mt2216-9-v2-1100kv-motor/
Seems they have good bearings. I've had about 1000 flights on them and no trouble yet.
Maybe a summary on the original post would be good to list the best recommendations. I'm going to stop lubricating mine and just take them apart once or twice a year to clean them. Would acetone be the best product to use for that?
yes, acetone is the best. Some places suggest paint thinners, but these can leave behind a residue.
remove as much of the shielding as you can, however I would leave the cage in and agitate the bearings more - if you remove the cage then be careful to keep the same ball spacing - if they slip around to one side the bearing comes apart completely and it's more hassle than it's worth to get it all back together.
I wouldn't ever use citrus cleaners, it leaves a residue and takes forever to dry. Acetone evaporates so nicely.
Ceramic bearings can run without lube, but they're $$$$. I'd expect they'd be nice inside a multirotor/plane motor since they don't have the abrupt shocks that can kill them quickly.
edit: this page has a technical document on those bearings: http://www.astbearings.com/ezo-bearings-catalog.html
I guess there is no problem with the acetone contacting the windings.
Another contribution: Hugues post a Tiger motor with High grade EZO bearings that recommend change before 60 hurs flying time.
So my flights are 15 minutes, thus 60 hours is 240 flights and I guess that the Hugues post is no lube just a change out?
Is our conclusion that lubrication every 6 flights is not needed?
Did I miss something,or do we not know what motors are used in the IRIS+?...(no disrespect for other
craft intended)
Almost none of the bearings used in multicopter motors have removable shields and many of them are not simply shielded, but in fact sealed.
The thinner oil or grease - (Superlube) I have recommended will in fact penetrate most shields, but generally not sealed bearings (and you do not want to inject through or under a rubber sealed bearing.
So far the only company I have seen that has any data regarding their bearings is Tiger Motor who have a bearing replacement schedule for their large motors based on hours of use.
Basically most manufacturers of quality motors supply replacement bearings and expect you to simply replace them when they become worn out (ostensibly due to the fact that they are not disassembleable).
Older motors like Scorpion recommended lubricating (and even had their own lubricant).
But almost all bearings have shields or seals now and information about lubrication has become very sparse.
I am actually glad to see the response you got from 3DR, at least they also appear to have figured out this isn't as simple as they thought it was.
KDE motors have the biggest, best bearings they can stuff in them and most of them have a 3 bearing stack (which is pretty much unique).
Some of them especially their bigger ones are sealed and the rest are shielded.
KDEs motors will outlast (and outperform) any other motor in the same size and weight class, period.
So far none of the motors have adopted proper thrust bearings which is what is really needed for multicopter use, so the best we can do is get ones with the highest quality largest conrad style ABEC bearings we can.
It is possible that ceramic or boron nitride like are available from Boca Bearing might provide extended life, but they can be fussy too.
http://www.bocabearings.com/bearing-applications/rc-bearings
Or these hybrid ceramics
http://www.trbrc.com/category-s/364.htm?gclid=Cj0KEQiAsdCnBRC86PeFk...
Best regards,
Gary
Hi Whooper,
That first link is a really excellent and thorough article.
The article is 12 years old however and is referring to the bearings used in RC fuel engines.
Circumstances for fuel engines are quite a bit different.
Most bearings in those motors are open and those that aren't are almost always shielded - not sealed.
He speaks of sealed bearings, but does not differentiate between sealed and shielded bearings and the bearings he is referring to that his greaser can grease are really shielded, not sealed.
You really couldn't grease actual sealed bearings with that technique, it would simply compress the seal against the side of the bearing and no grease would enter the bearing.
That said, it is a cool device and for those beartings where it would work where you have removed them from the motor, you could use it.
However,. by the time you have removed a bearing from the motor, it is probably a better idea to replace it anyway.
Also, he is talking about heavy lithium based greases, which would work fine for highly stressed fuel engines, but really are not well suited for our electric motors.
Generally you need a lighter grade grease or oil for our motors and modern Teflon additive is in such small micro particles it definitely does not produce a gritty condition for even the tiniest of bearings and it is an excellent - probably the best additive for our use.
Teflon micro lubricants really weren't yet commercially available when he wrote that article.
RC fuel engines are also subject to bearing wash-down from the solvent type fuels used, our electric motors are not.
It is possible that there are some bearings for some motors that would benefit from this, but mostly, if the lubricant won't wick into the bearing while it is still in the motor (open and many shielded bearings), I would generally recommend simply replacing it if you need to remove the bearing.
If I were using fuel RC motors with ball bearings I would probably buy one of these, otherwise probably not.
Tiger motor recommends a "small drop of lubrication oil on each bearing every 5 or six flights".
Light machine oil (or super lube oil or light grease) will probably penetrate the shields that T-Motor uses on most of their bearings, a heavier automotive style grease (such as this tool is designed for) would not.
And a light oil or grease is what is needed for our motors.
Best Regards,
Gary
All the motors I have seen have shielded/sealed bearings, even $10 ones from hobbyking.
Shielded bearings can be lubricated if the shields are removable like Steven Adams described. You can google "how to lubricate inline skate bearings". It's not a short process. It's probably more reasonable to buy new bearings.
Lubricating by letting oil wick into the bearing is a bad idea. It's pretty sure that you'll get some oil on the outside of the shield and this oil will only collect dust. This dust on top of the shield will unavoidably get into the bearing.
Just got a reply from 3DR
"In regards the motor lubrication; unfortunately we have no guidelines on this at the time, but I'll make sure to bring it up to see if there's any pointers we can share."
So my action item to find out what 3DR recommends is done, yet still no specific guidance.
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