Boca bearings upgrades for Tiger(Avroto) motors.

[jes1111]

what are you flying these days Jes? Last I heard you had something on the drawing board.

The Boca site had a promotion at the end of last year, 50% your whole order so I stocked up. If I have some time later I'll test your theory that they should be less money elsewhere but your Abec1 is the same price as the Abec5 I quoted. The difference is mine is shielded, yours is sealed. The only place I'm seeing a sealed bearing as possibly required is the top position on an inverted motor, everywhere else they're holding up fine.

Regarding your comment about our speed rating, by what I've been able to tell, ours is actually a low speed application for these bearings which should make the grease a lifetime lube. Out-of-round bearing races may make things heat up a lot more and make the grease melt out but lubrication shouldn't be necessary if everything else is normal.

Good discussion.

Bart

I've built two "mules" for testing out various frame and gimbal ideas, but so far I'm only flying for that purpose.

Boca, of course, are a niche supplier - they charge a hefty premium for bringing standard industrial components together in one place and describing/supporting them for specific "amateur" applications. They trade heavily on the "cool factor" of ceramics, orange rubber seals and using descriptions like "Grease Power Lightning Lube" to sell standard lithium grease at an inflated price

Actually I haven't used sealed bearings yet - I, too, bought in bulk (before I'd thought of using sealed) so I have about 100 bearings left to get through, at which time I will switch to sealed units. Incidentally, one of the other advantages of rubber-sealed bearings is that you can very easily remove/refit the shields to wash out the interior, inspect and re-grease - that in itself may make them a better bet.

Regarding the speed rating - yes, in pure rotational speed terms, this is a low-speed application. But, as I said in one of my long posts, the heat, vibration and operating environment to which we subject these bearing strongly suggests "de-rating" them, i.e. treating them as if they are in a "high speed, harsh environment" application.

Jes is there a rule of thumb for how long till we should replace bearings?. I finally have a machine I am happy with and it's doing a decent number of flights so I'm wondering about the frequency of maintenance of bearings etc.

That's a difficult question - the only way to establish the answer mechanically is to record and graph failures in use and then apply a safety factor, i.e. wait till you've crashed enough times due to bearing failure to establish the pattern. In practise that would be a long and expensive exercise - so I believe the way to approach it is from a cost viewpoint: get a supply of bearings and then decide how much "cost per flight" you are prepared to allocate to regular bearing replacement. If the bearings cost you $2 each and you have an octo then that's $32 per set - replacing them after every 8 flights would cost you $4 per flight, every 16 flights is $2 per flight, etc. - I've settled myself on 30 flights, about $1.00 per flight. Not an unreasonable "consumables" cost, is it? Incidentally, 30 flights of 15 minutes each at an average of 6000rpm adds up to about 3 million revolutions for each bearing - considering the above-mentioned "harsh environment" that's a fair amount of work for those tiny little balls!

If you have good quality bearings and off course no crashed you wont change them..

So if I have a "good quality" hard disk I don't need to make backups of my important data?

 

[jes1111]

Out-of-round bearing races may make things heat up a lot more...

If the bearing bore is distorted it will force the outer race out-of-round. Such distortion should be pretty obvious if you offer the bearing to the bore (with your fingers switched to "sensitive mode"). If you do find an out-of-round bearing bore then that motor is basically junk, I'd say.

 

[DucktileMedia]

I had my first run with Bocas and I have to say I am not pleased. I spun the bell/shaft assembly in each bearing and they feel like they have slightly more play than the EZO. once assembled, they are VERY fragile. My bearings had so much slop and click that the video was barely salvageable from this last wedding I did. Today I replaced the BOCA's with other BOCAs and I was much more careful in installing them. But they still have a noticeable clicking noise which i am sure will come out on the video. All in all I have to say none of my other 14 avrotos or Tmotors do this. Perhaps there is a break in period? The used motors should not be tighter in tolerances than a motor with fresh bearings! And at 3x the cost!

 

[jes1111]

I had my first run with Bocas and I have to say I am not pleased. I spun the bell/shaft assembly in each bearing and they feel like they have slightly more play than the EZO. once assembled, they are VERY fragile. My bearings had so much slop and click that the video was barely salvageable from this last wedding I did. Today I replaced the BOCA's with other BOCAs and I was much more careful in installing them. But they still have a noticeable clicking noise which i am sure will come out on the video. All in all I have to say none of my other 14 avrotos or Tmotors do this. Perhaps there is a break in period? The used motors should not be tighter in tolerances than a motor with fresh bearings! And at 3x the cost!

Which model/spec Boca bearing did you get? Are there any markings on them?

 

[DucktileMedia]

Ill post it tomorrow. yes, there is a laser print of something on the side. I could hear a mechanical slapping when the heli was taking off. I'd post the video but i dont want to give you guys a headache. from now on I'm just buying 2 extra motors and not messing with this crap.

 

[RTRyder]

I have a different methodology on motor bearings. First I don't buy cheap (meaning crappy) motors unless I plan on them having short lifespans, i.e. the ones I use on aerobatic quads, sometimes you just have to make sacrifices to the multirotor gods to keep things in balance.

Any motor I care about gets regular maintenance, every 10 flights they get cleaned out with a can of compressed air, inspected for any potential problems, and the bearings lubed top and bottom. Using this method the Roxxy motors on my original MK hexa are currently at right around 23 hours total run/flight time and are all in perfect condition.

I fully agree with the buy extra motors method as well, the time it takes to properly replace bearings in these motors is hard to justify unless its an AXI or equivalent price range and even then I'm not sure if I'd bother. Then again, properly maintained the likelihood of bearing failure is reduced to the point that the motor is probably due for replacement anyway by the time the bearings are shot if they were good quality to begin with.

Ken

 

[DucktileMedia]

I'd agree with almost everything you just said except for the every 10 flights. You mentioned lubing the front and backs of both bearings every 10 flights? that would involve taking the motor apart which would potentially be more harmful to the motor than just leaving it alone. My motors are totally fine, I only have this issue because I had to intentionally crash the heli as I didnt know what was keeping the heli from landing (AH!!). other than this all my other motors are excellent and have zero maintenance.

 

[RTRyder]

I'd agree with almost everything you just said except for the every 10 flights. You mentioned lubing the front and backs of both bearings every 10 flights? that would involve taking the motor apart which would potentially be more harmful to the motor than just leaving it alone. My motors are totally fine, I only have this issue because I had to intentionally crash the heli as I didnt know what was keeping the heli from landing (AH!!). other than this all my other motors are excellent and have zero maintenance.

Not front and back, top and bottom. I lube all the top bearings and give plenty of time for the lube to sink into the bearing, then I flip it upside down and lube the bottom bearings from underneath, assuming the frame allows access to do so. If not I have to unbolt the motor from the mount but I think most of what I have flying right now has access without removing the motor so not a problem.

Ken

 

[PaNt]

i put the new Boca bearings to my tiger motors..!
The Ezo were in good condition but i changed them.! Now on the new BOCA good quality i lube them or not?

Thank you!

 

[PaNt]

i put the new Boca bearings to my tiger motors..!
The Ezo were in good condition but i changed them.! Now on the new BOCA good quality i lube them or not?

Thank you!

OK i lube them ...!

But there is a little play to all motors..! what you think is this a problem or not?? i Put the Ceramic Boca bearings.!

Thank you!

 

[DucktileMedia]

Pant, I would not lube them but thats not the reason for your play. I got it too. There are a few things going on here, at least for me. First things first, you have to be VERY careful with these BOCA's to not put ANY pressure on the inner race. Bart has specifically made a tool that he had machined just for this very reason. I tried using a washer at first and squeezed the 2 bearings in using a nut/bolt. But what happened was the washer was putting a bit of pressure on the inner race and I could definitely hear and feel a bumpyness. Not good. The other thing is to make sure your end play is tight. I think different washers/ c lips have a very slight difference in tolerance and it is hard to tell sometimes if the slop is lateral or only end play. When you spin the motor in your hand you may feel like there is lateral play which is actually jus the end play of the motor being taken up when you spin it. But if you can push the bell housing in to take the slack out and you can move it at all side to side, you have serious problems that will show up in your video.

I personally think the best thing to do is to not lube your bearings and replace them anytime you have the slightest hesitation they are not perfect. Get one of Bart's bearing presses and keep some EZO or BOCA's on hand. Bearings come sealed with the correct grease in them already. Lubing them will attract dirt and dilute the proper grease thats in there already. But I cant back this up with science so it is therefore an opinion.


http://www.multirotorforums.com/showthread.php?6648-Motor-Bearing-Press-Tool&highlight=bearing+press

 

[Bartman]

i posted a video showing bearing replacement with the Tiger/Avroto/QC 2814 motors and have the tool for sale in the classifieds. I'm picking up the parts for the tool this week and should be shipping by Friday. We're in the middle of a hurricane though so this is depending on my being able to get out of the driveway and onto the major roads before too long. Will also have the tool ready for the smaller Tiger 2212/2216 motors.

http://www.multirotorforums.com/sho...-brushless-motors&highlight=changing+bearings

Bart

 

[PaNt]

Pant, I would not lube them but thats not the reason for your play. I got it too. There are a few things going on here, at least for me. First things first, you have to be VERY careful with these BOCA's to not put ANY pressure on the inner race. Bart has specifically made a tool that he had machined just for this very reason. I tried using a washer at first and squeezed the 2 bearings in using a nut/bolt. But what happened was the washer was putting a bit of pressure on the inner race and I could definitely hear and feel a bumpyness. Not good. The other thing is to make sure your end play is tight. I think different washers/ c lips have a very slight difference in tolerance and it is hard to tell sometimes if the slop is lateral or only end play. When you spin the motor in your hand you may feel like there is lateral play which is actually jus the end play of the motor being taken up when you spin it. But if you can push the bell housing in to take the slack out and you can move it at all side to side, you have serious problems that will show up in your video.

I personally think the best thing to do is to not lube your bearings and replace them anytime you have the slightest hesitation they are not perfect. Get one of Bart's bearing presses and keep some EZO or BOCA's on hand. Bearings come sealed with the correct grease in them already. Lubing them will attract dirt and dilute the proper grease thats in there already. But I cant back this up with science so it is therefore an opinion.


http://www.multirotorforums.com/showthread.php?6648-Motor-Bearing-Press-Tool&highlight=bearing+press

First of all i did everything with Barts perfect tool...! THe Tool is pefect GUYS...!!

Secondly i lube them because Sunil from Boca told me that there is not problem to lube them on the outside of the bearing..!

And the play is from Boca bearings..! !!! when i do the motor up and down there is no play there is a play when i do the motor from left to right and the opposite(lateral play??)..! It seems to be from the new bearings.. Its a very small play.. is this a problem?

 

[Bartman]

Thanks PaNt for the endorsement. You got one of the five prototype sets I had made before going ahead with a full production run. I'm glad it worked out for you. I don't see the same amount of play you're talking about with the Boca bearings. Which grade of bearing did you buy? Have a model number from Boca?

For the Tiger motors with the noisy bearings, try blowing air through the bell down into the motor to dislodge any small debris that may be in there. I wouldn't fret over the noisy bearings until you've had a chance to run them a bit and see if they break-in and quiet down.

 

[PaNt]

Thanks PaNt for the endorsement. You got one of the five prototype sets I had made before going ahead with a full production run. I'm glad it worked out for you. I don't see the same amount of play you're talking about with the Boca bearings. Which grade of bearing did you buy? Have a model number from Boca?

For the Tiger motors with the noisy bearings, try blowing air through the bell down into the motor to dislodge any small debris that may be in there. I wouldn't fret over the noisy bearings until you've had a chance to run them a bit and see if they break-in and quiet down.

I baught these here..!

http://www.bocabearings.com/bearing...eramic-lightning-abec-5/t-motor-mt2814-710-kv

 

[Bartman]

i'm not sure why you'd have lateral movement in the new bearings. for what it's worth, the ceramic bearings are wayyyy overkill. our application is considered a low RPM use so ceramics aren't necessary. some will say that the ABEC 5 is even too much but I buy them at the end of the year when Boca has their big sale so the price is more reasonable.

have your motors ever been crashed? ever change the bearings before you had my preess-tool and maybe elongated the bearing seats? probably not, right? do you have a micrometer? can you measure the OD of the motor shaft? high end bearings should be pretty dead on as far as the inside diameter of the bearing goes.

 

[Bartman]

Pant,.............http://www.multirotorforums.com/showthread.php?6648-Motor-Bearing-Press-Tool&highlight=bearing+press

i didn't see your post when i put mine up Yuri. thanks for the plug.

 

[Bartman]

also, keep in mind with a low RPM application, the grease is perfectly suited for the job and should last a long time.

these are small and very fragile bearings. when in proper use they last a long time but when the prop makes impact with something or when the props are out of balance, the delicate inner races will warp/distort and soon thereafter the bearing will start to make noise. the bearings closest to the prop might survive a prop strike ok but chance are very good that the inner race on the side opposite the prop will elongate from the force of the prop strike and cause the bearing to fail.

the moral of the story is, don't hit anything and really balance your props well.

 

[PaNt]

i'm not sure why you'd have lateral movement in the new bearings. for what it's worth, the ceramic bearings are wayyyy overkill. our application is considered a low RPM use so ceramics aren't necessary. some will say that the ABEC 5 is even too much but I buy them at the end of the year when Boca has their big sale so the price is more reasonable.

have your motors ever been crashed? ever change the bearings before you had my preess-tool and maybe elongated the bearing seats? probably not, right? do you have a micrometer? can you measure the OD of the motor shaft? high end bearings should be pretty dead on as far as the inside diameter of the bearing goes.

Never crashed an the play is very very small..!! with the stock there was no play..

Also i cleaned everything when i opened the bearings..!

 

[Bartman]

i'll measure a motor shaft when i go downstairs. i doubt Tiger would deliberately undersize the shafts so you have to buy bearings from them but who knows?!?