There wasn’t a grub on the shaft?
TIL another name for circlip
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PL Wiki (Seger ring) :
EN Wiki (Circlip):
So yea, there is a few xD
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Probably some kind of epoxy. Localized heat (careful not to overheat the magnets) and/or solvent should help. I’ve had decent luck with MEK.
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Well this was a dead end. Let it be known, there is a ~3/8" - 1/2" long plug of adhesive, no grub screw of any kind.
I used my backup iron to melt through rather than hit it with generalized heat and risk damage elsewhere. Took a few minutes of digging, but got through to this:
Thru hole to a cavity on the other side. Will disassemble the stator from the rotor here shortly and investigate further
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That’s odd because I always heard them called “Jesus Rings” in the 1980s and 90s because only Jesus knew how to remove them.
This was before a quick internet search would locate a $10 circlip tool on Amazon.
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Sorry man I honestly thought they would have to secure the shaft to the rotor somewhere but alas, apologies for the wasted time.
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Eh no worries, we all learned something today 
Super interesting to disassemble a brushless outrunner - never pulled one of these apart.
One snap ring + one wave washer, quick pull, easy peasy (thanks @b264 for the guide)
Great coverage across the sensor pcb
I always wondered if the FS-BH motors had the possibility for mounting screws going too deep and shorting on the windings. I tried - it seems like the mounting holes aren’t fully threaded. The fasteners stop right at the edge.
Good epoxy/adhesive on the sensor wires too
Dual bearings top and bottom on the stator, looked in good shape.
For those who may need replacements - NMB R-2210KK made in Thailand.
Confirmed again - no grub screw on the bottom. It’s a bunch of the battle hardening glue packed in the hole. Probably used during assembly somehow.
The reason I tore this one apart is that I have had a high pitched ‘cricket chirp’ sound coming from this motor. I noticed the bell taps the stator at one point, just barely, in every revolution.
I confirmed this - there’s a very slight amount of wiggle to the axle. The bottom of the axle has a hole, which at first glance appears to be a hex head. I tried every allen key I have - metric and imperial - no dice. Upon closer inspection, it is not a hex. It’s a round hole with a lead-in chamfer. My guess is that it’s used to press-fit the axle in place during assembly.
So… now what?! I could try to press the axle out with a hydraulic press, but I’m not sure how I would even fix this. Or how I would line everything up correctly to epoxy it in place.
Orrr I can just take the bell to a belt sander and grind off 2mm and live with it… it works perfect otherwise.
Anyone want to throw an opinion in here?
@Fosterqc you ever get around to swapping shafts?
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It’s probably how they secure the axle in the machine that makes the axle. (likely a lathe)
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Found a fun new problem while i was in there:
Broken winding… fuuuuk
Interesting that I never had a performance problem with this motor though. Is it worth it to clean the varnish and solder back together?
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Hmm do you have the detection results from before taking apart? Then you can compare to after you resolder that broken winding.
I am still trying to figure out why there is no grub screw. What is locking the rotation of the can to axle?? Not just glue surely.
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Ok, here is the final, hard won truth. I scienced this motor, because SCIENCE.
There are two small M4 set screws hidden deep within the blue epoxy filling both holes in the can. The shaft has two unthreaded cavities to align with those set screws.
If you’re going to replace a shaft in the latest gen Flipsky motors, I recommend drilling both holes out with a 7/64" (or 3mm) drill bit. There’s the outer plug, a gap, and then an interior plug on top of the set screw. You’ll know when you’ve hit the set screw - be gentle. Should take a 2mm hex key. You may have to dig out chunks of epoxy to get the hex key to bite.
Or, you can be like me and put the entire can under a hydraulic press.
Don’t be like me.
Now… after I check this steel shaft for straightness (which it most likely is still perfectly good), should I fill the aluminum can shaft hole with JBWeld and use a drill press to create a new, tighter mounting hole? Or see what high strength retaining compound can do instead?
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Never trust adhesives.
Go for the epoxy
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Is there a more permanent epoxy than JBWeld?
There are lots of different epoxies. JB Weld is a very hard epoxy. West System 650 would be the opposite of that. Both are hard, but JB Weld 8265 Original Steel is hard hard, like metal, you can drill and tap it and bolt to it. WS 650 is hard but not brittle hard. JB Weld 8265 can be cracked.
And then you have a bunch of other epoxies that are between those two, and then probably a million epoxies I have never even used.
If you only want to buy one, I’d get West System 105 + 206 OR Silvertip Epoxy, they are great all-purpose epoxies IMHO
For a rotor to shaft bond I would probably want a hard epoxy so it was less likely to work its way crooked.
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Make sure you clean the surface very well and even sand it lightly to ensure there are no oils on it.
And always, ALWAYS mix exactly according to directions. Exactly. Including stir time and everything.
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Ok, another option I was thinking about last night -
- Get a 10mm aluminum round bar, ideally oversized.
- Cut to length and epoxy into the hole.
- Clean up / face the end.
- Find the can center point (this will be the hard part)
- Drill press new hole, slight interference fit
- (Optional) drill out old set screw holes and tap one size larger
- Freeze old shaft
- Install shaft, epoxy in place (epoxy + cold may not work, but need some way to fix rotation, tbd)
This all basically amounts to an aluminum sleeve vs only epoxy. Which I like slightly better.
I was half right
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