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Author Topic: Outrunner motor rotor movement.  (Read 563 times)

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Offline cheddar-caveman

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Outrunner motor rotor movement.
« on: September 08, 2018, 18:33:42 PM »
Is it "normal" for the rotor of an out-runner motor to move away from the stator when under load from a propeller?

Just run my Turnigy 3648 up on a test stand and noticed quite significant movement of the rotor - about 5mm. When stopped I could pull the rotor away from the stator, sort of "springy", so I guess there is some sort of thrust bearing in there?

ila_rendered  ila_rendered

Just curious.........
« Last Edit: September 08, 2018, 18:36:46 PM by cheddar-caveman »


Offline Chippie

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Re: Outrunner motor rotor movement.
« Reply #1 on: September 08, 2018, 18:46:34 PM »
There shouldnt be any endfloat...
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Offline cheddar-caveman

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Re: Outrunner motor rotor movement.
« Reply #2 on: September 08, 2018, 20:33:49 PM »
Oh! It's a brand new motor from HK! I'll get in touch with them..........


Offline PDR

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Re: Outrunner motor rotor movement.
« Reply #3 on: September 08, 2018, 20:44:49 PM »
On most outrunners when rear-mounted the rotor is free to float, and usually constrained by either a circlip or a collet on the shaft just behind the rear bearing. The "axial springiness" you can feel is just the magnets of the rotor aligning themselves with the magnetic centre of the stator.

If there isn't a collet there (it's usually supplied in the accessories pack) and there is no circlip in a groove then it's easy enough to just bung a collet on yourself. Certainly less hassle than trying to get HK to supply one...

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Offline cheddar-caveman

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Re: Outrunner motor rotor movement.
« Reply #4 on: September 08, 2018, 21:51:28 PM »
Had a chat with HK "Chat" help and all sorted. It would appear that the shaft was incorrectly located in the rotor, "sticking out" a bit at the rear bearing...........
ila_rendered

Removed the two grub screws in the end housing at the prop end, which lock the shaft to the rotor housing.
Opened vice jaws just enough to allow the shaft to go down between them and allow the end housing to sit on the jaws.
Using small tack hammer, tapped the end of the shaft that was sticking out and presto! Shaft went back to where it should be.
Replaced and tightened the two grub screws, job done!

Flipping powerful magnets in there!!


 

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