I’ve been looking for outrunner motors with an additional support bearing at the rotor.
The question is simple: What is the smallest (or lightest) motor that still has a support bearing?
I know the SK3 6364 and 6374 have it (got both in builds and opened them at least once), still the SK3 6354 doesn’t have it. Parallel the SK3 5045, SK3 5055 don’t have a support bearing, but the SK3 5065 does have it.
I found this out by searching for replacement parts and Hobbyking has been selling them and still shows it on the replacement bearing picture.
But I can’t find any information about the SK8 series. Hobbyking has no replacement parts for them and by the pictures I can’t see it.
Did anyone ever open a SK8 motor?
Does anyone know of other motors using a support bearing?
So far the lightest I found is the SK3 5065 at ~520gr.
By other motors I was thinking in the direction of hub motors. I guess every hub motor is supported from two sides, but which of them are on the light side?
Lol, thats ridiculous, why should a plastic fan need an additional bearing? I don’t think this 10g plastic and 5g thrust needs a 38mm ball bearing with a 3.8 kN rating
This bearing is supporting the Can from the other side to guarantee a smooth concentric rotation.
The bearing doubles up as a seal. If a motor got the support bearing I want to disassemble it, fill the fan with silicone and afterwards fill the motor with automatic transmission oil (very thin oil).
That helps cooling the motor by a factor of 2-5 times.
Can you explain what the shaft diameter has to do with the support of the rotor?
I mean you are right it kinda supports the rotor because the can is bolted to the plastic fan but I’m not sure if the plastic is rigid enough. It’s better than nothing but makes the motor heavier and bigger.
That sounds interesting
I have some experience in killing motors and had quite the same accident with 2 different motors when I crashed them into the same concrete obstacle while riding in reverse in skate park.
The motor with 8mm shaft instantly died, it was stuck with broken magnets. The motor with 10mm shaft survived, there is a slight wobble in the can because the shaft is slightly bent but I still use this motor without problems. So a bigger shaft “supports” and protects the rotor much better that’s what I meant in my post.
you are right it makes it heavier, but also a lot more rigid, just try to bend the cans of 6374 with and without support.
Well, you wont find anything handling impact forces. Every bearing gets easily destroyed by an impact load. Same for every other metal part.
Use a plastic bumper to cover impacts, like cars do…
that’s not a support, it’s just more rigid, but for normal use it is just heavier…(I don’t think crashing into things and having the motor as bumper is a valid use case scenario).
Still we are getting off topic.
Nobody ever disassembled a SK8 motor?
about the bearing size I’m not sure, the OD of the “ring” is 18mm so I would say the bearing OD is max. 15mm. The chance is big that SK3 use the same bearings.
The 6384 is much stronger than the SK8 6374 and the funny thing is that it’s bigger inside plus smaller outside but same weight. But one good thing about SK8, they are dead silent in FOC.
Thanks!
Didn’t imagine that the stator diameter is that much smaller but the outer diameter almost same.
I mean both just have a aluminium can with some magnets glued it.
So the question now is: How does the smaller SK8 motors look like?
Anyone opened a SK8 50xx?
