Replacing bearings in brushless motors

Bartman

Welcome to MultiRotorForums.com!!
I've put together a video showing the use of a small tool I've designed to make changing bearings much easier. The tool is available for sale in the classifieds area.

Thanks,
Bart

 
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jes1111

Active Member
Neat idea!

Small point - I would recommend using a shim washer even on "the top of the bottom motor". It is a shim washer, i.e it's designed to create the correct amount of end-play between the bell and the stator. Leaving it out will allow the bell to climb up and down the shaft - not desirable.
 

Bartman

Welcome to MultiRotorForums.com!!
The washer is absolutely necessary in motors that are mounted upright. On the motors of a coaxial heli, the bottom motors are upside down and the props push the bell up against the base of the motor. In this case the washer isn't doing anything except bouncing around and making metal dust. I pulled one motor that was mounted inverted and the washer had worn away to almost nothing. The magnetic pull of the magnets is already holding the bell tight to the motor base, when the bottom props start turning they are just pushing the bell more against the base.

If someone isn't comfortable omitting the washer then it's perfectly fine to just put a replacement washer in there when they reassemble the motor. Upright motors should always have the washer in there.

Bart
 

DucktileMedia

Drone Enthusiast
I can say from trying to use a standard washer and bolt that a tool like this would be awesome. I had no idea how sensitive the inner race was to being pushed in place. It actually made my brand new bearings "tick" as the motor turns essentially ruining all of my footage from this one project! So count me in for an order when they are available.
 
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jes1111

Active Member
I can understand that the cheapo "washers" that come with many motors may well be made of cream cheese. But well-made shims in carbon steel should not wimp out as you describe. The shim (or shims) should occupy all the available space between the face of the inner race and the circlip, without actually putting pressure on the circlip, thus preventing the bell from being able to move axially (which it probably will do even though the prop is pushing that motor upwards - vibration does strange things). If the existing/original shim is not the correct thickness then it will wear more quickly - exactly the phenomenon that "shimming out" the shaft seeks to avoid.

Probably a small point, though - no biggie if the shim is omitted, so long as your inspection/maintenance routine is thorough and regular ;) - as with all things MR, the more you pay for the components the more you'll want to keep them in A1 shape.
 


Bartman

Welcome to MultiRotorForums.com!!
I've measured a bunch of clips and washers to come to the following conclusion

the original washers are .020" thick, the washers I'm supplying are 0.015 to 0.020" thick. i believe the .005" (max) difference to be negligible. I am going to test how much weight it takes to pull the bell tight against the spring clip with the hypothesis that the props make that much thrust or more at idle thus negating the gap in flight.

the original spring clips are .015" thick and the spring clips I'm providing with my bearing tool are identical in design and thickness.

i've actually had trouble with the original washers where they were a tad too thick and made installing the spring clip difficult. in fact, i suspect it was an improperly installed spring clip (back when I used to reuse the washers) that allowed a bell to fly off of one of my helicopters causing a minor crash.

more on this to come. thanks for the early orders, I appreciate it. :)

I forgot to mention in the ads that the aluminum tool parts will be anodized yellow. :triumphant:
 



gtranquilla

RadioActive
My pan style motors seem to have a 6 mm motor shaft diameter and the bearing OD appears to be 12.5mm..... Am I out of luck with respect to the tools you provide?
 

Bartman

Welcome to MultiRotorForums.com!!
My pan style motors seem to have a 6 mm motor shaft diameter and the bearing OD appears to be 12.5mm..... Am I out of luck with respect to the tools you provide?

I"m sorry but yes, the tools i make won't help. The 4mm ID tool has been used to push Tiger MT-3515 bearings into place even though the ID is different (OD is the same) but if the tool can't bear against the outer race of the bearing while not touching the inner race then it will just do damage as it's pushing.

Bart
 


gtranquilla

RadioActive
The basic concept remains the most valid I have seen for any size bearing so I will attempt to follow it for the larger bearings.....It's a great idea!
I"m sorry but yes, the tools i make won't help. The 4mm ID tool has been used to push Tiger MT-3515 bearings into place even though the ID is different (OD is the same) but if the tool can't bear against the outer race of the bearing while not touching the inner race then it will just do damage as it's pushing.

Bart
 



gtranquilla

RadioActive
I've followed your example for the new pancake style motors such as Hengli and Turnigy that use a widely available 686ZZ bearing. Pancake style motors have winding exposed for easy damage when changing bearings as I can attest..... destroyed my first motor in a matter of seconds.
I sourced the bearings, shaft clips and a jig to hold the motor so that the windings don't get damaged. Trying to put together a kit and a video now for it should anyone be interested.
 

Chalagi

Member
I have 2 different types of bearing replacement tools but I have only used one of them for a 4MM shaft and it worked great.
 

peterfreeman

New Member
Neat idea!

Small point - I would recommend using a shim washer even on "the top of the bottom motor". It is a shim washer, i.e it's designed Customer service skills, cps hr consulting, management consulting internships, sample strategic plan, marketing plan examples, android programming language,qualities of a leader,D&P,DNP,dandpto create the correct amount of end-play between the bell and the stator. Leaving it out will allow the bell to climb up and down the shaft - not desirable.
i agree
 
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Bartman

Welcome to MultiRotorForums.com!!

i've since said I don't leave it out but what JES111 said was incorrect as bell on the bottom motor is being pushed up and therefore the washer wouldn't be shimming anything.

i now leave it in there regardless of motor orientation as it may keep the bearing from floating out of its race if it isn't in there tightly.

Bart
 

gtranquilla

RadioActive
BTW - I have all the other parts to make up complete kits including replacement circ-clips or retainer clips but am having trouble finding shim washers.

Anyone know where I can source these...?


These kits are for the new pancake style motors with a 6mm shaft diameter and use the very common RC bearing size 686ZZ.




i've since said I don't leave it out but what JES111 said was incorrect as bell on the bottom motor is being pushed up and therefore the washer wouldn't be shimming anything.

i now leave it in there regardless of motor orientation as it may keep the bearing from floating out of its race if it isn't in there tightly.

Bart
 

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