DD hub Magnets rubbing Stator after adding Statorade

[hias9]

On a 3000W 45mm magnet height hub motor I added some Statorade. Now the magnets seem to rub on the stator.

I took a little video of it: https://files.fm/u/bnfztptnn

I marked the sidecovers before and installed them the same way like they were installed before.

I already tried using different sidecovers, replacing the bearings, removing shaft seals and adding/removing bearing spacers. Nothing helped.
I can only say for sure that it is not the windings rubbing on a sidecover, so it seems to be the magnets rubbing on the stator.

Without the wheel installed, when turning the axle with a 10mm wrench it is barely hearable when turning the axle very slowly, but clearly hearable when turning the axle faster.

Does anybody have an idea what could solve this?

 

[speedmd]

Sounds like the stator may have also slipped or gotten distorted on the axle if it was less than perfectly snug. Clip holding it in place? Side covers if not machined snug will not hold rotor position with enough precision for close fits. Not sure the magnet ring on most would hold shape once the covers get loosened if the spoke tension varies much at all. The whole design is borderline at best from some factories.

I would think you be able to fix it with a large pair of calipers, and get the magnet ring as round as you can first. May need to be torn down if distorted significantly. After "centering" and screwing - gluing down the covers, rebuild your wheel.

 

[amberwolf]

FWIW, already-installed and tightly secured, well-fitting side covers could prevent rotor distortion under spoke tension, but if the tension varied enough around the wheel, and the rotor is soft enough metal, then when the covers are removed, tension could then distort the rotor, and putting the side covers back on would not fix this or even show the problem existed, unless their lips were a *perfect* fit for the rotor, in which case they wouldn't go back on once removed (at least, not without significant force causing some of the lip to be shaved off at the points the rotor is smallest in diameter or off center towards the axle. Gaps would then exist wherever the rotor was it's largest diameter, or off-center towards the rim. This might be visible on the covers, depending on the previous surfaces they had.

From the descriptions you've given, and tests you've tried, and if you are certain the rotor is not distorted, the only place I can imagine that the problem could be is in the stator.

Some other things that could cause misalignment at an angle like that:
--axle could be machined incorrectly on one bearing shoulder.
--axle could be mounted at an angle in the stator supports.
--stator support axle hole could be machined incorrectly.
--stator supports could be bent or machined incorrectly.

If the angle of misalignment is tiny at the lamination/rotor interface, then the error in the stator could be very small and still be enough to cause the problem.

 

[hias9]

I won't have time the next days, but I am sure the problem is not on the stator/axle part, but has to be on the rotor/sidecover part.
Maybe I will then install another stator to test if the problem persists.
But the axle sits firmly inside the stator core and is additionally hold in place by a circlip.

 

[hias9]

So here is a little update on this.
I measured the rotor and it is round.
I eliminated the axial play (which was about 0.4mm) with additional washers.
Now the stator was sitting perfectly inside the rotor, but the noise did not change at all.

The noise is in fact caused by the Statorade. The noise is created by around 50 clicks per rotation (motor is 45mm magnet height, 46 poles 51 slots).
Through the holes I had drilled to verify stator position (I won’t ride with an open sidecover), I could see that at every click there is some Statorade displaced to the outside which causes this noise.
This rotor (like most 46 pole rotors) has flat magnets so airgap width varies slightly.

Video 1 is with about 10-12ml inside the motor: https://ufile.io/kdaukcny
Video 2 after removing the Statorade: https://ufile.io/xmuoibqe

After removing it I was re-adding Statorade (this time gradually through one of the holes).
When only adding 1-2ml the noise was only there until the Statorade had spreaded.
When there were 5ml inside, the noise did not go away completely after the Statorade had spreaded. However with 5ml inside it's way more quiet than with 10-12ml and it's there over a smaller rpm range only.

Video 3 is after re-adding 5ml of Statorade: https://ufile.io/0dckluam

I would like to compare it to a rotor with same slot/pole configuration but with curved magnets instead of flat magnets.
Does anybody have a 46 pole 51 slots motor with curved magnets?