Granite How important is ABEC rating in a motor bearing?

[Arrmature]

I've been searching a motor bearings for my Granite and Typhon 3S and haven't had much luck. After some back and forth with Boca, they have recommended these yellow seal bearings:

https://www.bocabearings.com/products/smr695c-2ys-nb2-7738

They seem to fit the bill quite nicely., my only concern being that they are rated ABEC 1. ABEC rating is typically a measure of how long the bearing will last. I'd really prefer ABEC 5, but I can't find anything. How concerned should I be with ABEC rating?

 

[Jerry-rigged]

ABEC has nothing to do with how long they last. ABEC is a rating of the bearing tolerances, and how easy/smooth they spin. ABEC 1 is good, ABEC 5 is great, ABEC 7 is silk, but will get killed with any grit.

One of my other hobbies is fishing. Here in Texas, we like to wade fish - that is, walk around in waste deep water for hours fishing... Our reels get wet, with salt water. For Wade fisherman, most will put ABEC 1 bearings in their reels. For boat fishermen, they will often use ABEC 5 or 7. But a bit of salt or sand will kill them pretty quick so most people will either run ABEC 1 in their wade gear, or plan on replacing their bearings often...

For a sealed brushless RC car motor - I would want ABEC 5 or 7 on the bell end, and maybe a 3 or 5 on the shaft end (depending on how dirty you think it will get). When I swapped bearings in my BLX185 motor, I put ABEC 5 ceramic bearings in. (At least, I think that is what they were... LOL)

 

[Arrmature]

ABEC has nothing to do with how long they last.

Yes and no - it all depends on the application. In fishing I would agree with you - the bearing speeds simply aren't high enough for eccentricity to shorten the bearing's life. When you spin the bearing at 40,000 rpm, the eccentricity becomes a more significant factor in the bearing's life. Having said that, I'm not having any luck in finding an ABEC5 or ABEC7 bearing that can handle 40,000 rpm. Most bearing suppliers don't list the rpm limit for their bearings, but when you ask, you get a limit that's too low.

 

[Be Ready]

Have you looked at the Jim’s bearing? They offer a ABEC 5 bearing.

 

[chrisexv6]

Yes and no - it all depends on the application. In fishing I would agree with you - the bearing speeds simply aren't high enough for eccentricity to shorten the bearing's life. When you spin the bearing at 40,000 rpm, the eccentricity becomes a more significant factor in the bearing's life. Having said that, I'm not having any luck in finding an ABEC5 or ABEC7 bearing that can handle 40,000 rpm. Most bearing suppliers don't list the rpm limit for their bearings, but when you ask, you get a limit that's too low.

Is it definitely 5mm shaft, 13mm od, 4mm width?

Literally just ordered that size bearing from McMaster-Carr (its the same size for the Hot Racing diff case of a Kraton).

 

[LMC]

Worth a read.

https://www.machinedesign.com/motor.../how-to-make-bearings-last-in-electric-motors

 

[slick2500]

I've been searching a motor bearings for my Granite and Typhon 3S and haven't had much luck. After some back and forth with Boca, they have recommended these yellow seal bearings:

https://www.bocabearings.com/products/smr695c-2ys-nb2-7738

They seem to fit the bill quite nicely., my only concern being that they are rated ABEC 1. ABEC rating is typically a measure of how long the bearing will last. I'd really prefer ABEC 5, but I can't find anything. How concerned should I be with ABEC rating?

Boca makes some Abec 7 this is just an example make sure that you order the right size. https://www.bocabearings.com/products/smr695c-2os-7-nb2-16647

 

[MrTitanium]

ABEC rating is strictly used for bearing tolerances. Bearing application is entirely up to the consumer and this rating does not reflect on this.

 

[Be Ready]

Boca makes some Abec 7 this is just an example make sure that you order the right size. https://www.bocabearings.com/products/smr695c-2os-7-nb2-16647

Dam... There proud of those... ?

 

[chrisexv6]

Dam... There proud of those... ?

I feel like a lot of RC stuff is just regular hardware but the "RC" moniker makes the price go up 2 or 3 times.

If they don't need to be ceramic its easy to find lower cost stainless metal or rubber shielded bearings.

 

[LMC]

I feel like a lot of RC stuff is just regular hardware but the "RC" moniker makes the price go up 2 or 3 times.

If they don't need to be ceramic its easy to find lower cost stainless metal or rubber shielded bearings.

The ones inside the motor should be ceramic, non conductive.

 

[chrisexv6]

The ones inside the motor should be ceramic, non conductive.

Good to know, thanks!

(new to the brushless world, will have to store that tidbit if the time ever comes....although it makes sense if I just took some time to think about it!)

 

[LMC]

Good to know, thanks!

(new to the brushless world, will have to store that tidbit if the time ever comes....although it makes sense if I just took some time to think about it!)

Happens in alternator bearings, arcs make pits, pits make bearing run hot, heat kills everything.

 

[Arrmature]

Have you looked at the Jim’s bearing? They offer a ABEC 5 bearing.

I have, but they are out of stock and have been for quite some time.

Boca makes some Abec 7 this is just an example make sure that you order the right size. https://www.bocabearings.com/products/smr695c-2os-7-nb2-16647

I did contact Boca about these bearings. The speed limit is 25,600 rpm, so they do not recommend these bearings in these motors - the bearing in my original post is what Boca recommends, but they are ABEC 1.

abec357.com sells a very similar orange shield bearing for a little less, but they state that the speed limit is 26,500 rpm.

TRBRC bearings seem to top out at 35,000 rpm, which is again too low.

 

[tdikyle]

I always find that my bearings outlast the seals, can the seals be bought separately?

 

[Arrmature]

Happens in alternator bearings, arcs make pits, pits make bearing run hot, heat kills everything.

Won't happen in this application. There is just no way to get a potential difference across the bearings in these cars.

 

[LMC]

Won't happen in this application. There is just no way to get a potential difference across the bearings in these cars.

Good to know, I wasn’t sure but I figured with the kind of power these things are running it might be an issue.

 

[Arrmature]

Good to know, I wasn’t sure but I figured with the kind of power these things are running it might be an issue.

The only way you'll get arcing in the bearings if there's a potential difference between the motor can and the rotor. The motor can should be electrically isolated from the coils (if it's not, you've got bigger problems) and the rotor isn't connected to anything electrical. The electrical system in these cars is a ground free system, unlike automobiles and industrial applications.

 

[LMC]

The only way you'll get arcing in the bearings if there's a potential difference between the motor can and the rotor. The motor can should be electrically isolated from the coils (if it's not, you've got bigger problems) and the rotor isn't connected to anything electrical. The electrical system in these cars is a ground free system, unlike automobiles and industrial applications.

I’m not a fan of electrical work and usually call the friend who knows about these things rather than learn about them myself. I’ll take greasy hands, stubborn bolts and missing knuckles over chasing electrical gremlins any day.

 

[LibertyMKiii]

My 2 cents is to get some basic rubber sealed bearings and create a routine that you service them (clean and re-oil/grease) after X number of hours or battery packs.