Nine Continent Disk Motors

[justin_le]

Optionally, as you say, a larger ID bearing could be used, if one exists that has the same OD. Or a different bearing with a ring adapter/spacer to fill the space the new one currently fills.

Good news! We got a big batch of spare covers and it turns out that the region with the protrusion for the disk mount is solid aluminum all the way through. So it is possible to simply bore out the original 11mm deep bearing cavity to a full 18.5mm or so. This way, the location of the ball bearing ends up being exactly at the same spot on the axle as it was with the curved non-disk side plates, and no axle machining or special bearing adapters are needed.

In the original disk side plates, cavity for the ball bearing is 11mm deep so that it sits more or less flush:


Disk plate is precisely centered on a lathe, and then the 35mm bearing hole is extended further back:
View attachment 2

Cavity now extends down to a little over 18mm deep


The ball bearing no longer sits flush, but is recessed to the right depth for where the bearing would be in the standard side cover:

Do you think the new rear sprocket side cover will fit the front 2807? I'd like to be able to try out a disc cover (front or rear) and a sprocket cover on my front 2807, if they'd fit.

So, that was the next moment or truth. I removed the side cover from a regular front Nine Continent motor. Replaced it with the modified disk version from the pictures above, and tried it out in bike fork. The disk sits about 2mm further to the right than would be ideal, but in this case there was enough side to side adjustment in the caliper mount to get it to align without rubbing the pads. In other cases, you could put a couple inside washers on the disk side of the axle to make the spacing better. So yeah, it works:

These narrower covers could allow me to use this motor where I might not have before, and use a disk or sprocket on either side without drilling into the cover itself.

I think so! -Justin

 

[justin_le]

Do you by chance know when these motors or covers will be available for purchase?
Thanks

We've got front / rear 20" disk motors in the 2805 winding and front / rear 26" motors in the 2806 windings in stock right now. Our next shipment will have disk options in the slower 2807 winding too, but for now it's just the 5 and 6 turn.

-Justin

 

[liveforphysics]

You rock Justin!

Great work!

 

[disndat]

Hey Justin any thoughts on selling bored out covers so users of the old style 9cs can use disk brakes?I have a 6x10 and a 2806 that I would love to get working with rear brakes again.

Thanks

 

[jmygann]

Can someone explain .... 9x7 , 6x10 ,2806, and 2807

 

[NickW]

Can someone explain .... 9x7 , 6x10 ,2806, and 2807

The last part of the number is the number of turns of wire on each pole of the motor.
The 28xx numbers are Justin's naming convention, where 28 is the magnet width iirc.

Lower numbers will go faster at a given voltage.
You'll get best performance with a winding matched to your battery voltage, wheel size, and planned cruising speed.

If you put that 6x10 on a mountain bike with a 36v battery, you would probably top out at 25km/h or so. (a guess)
If you put the 2806 on there, it'll be about right for a commuter, in the low to mid 30s,
If you were running at 60 or 72 volts, that 10 turn would be great, where the 06 would give you a silly high speed.

 

[Microbatman]

The number and thickness of winds are an important number.

HOWEVER

Another IMPORTANT and often OVERLOOKED number is the THICKNESS of the STATOR LAMINATIONS.This refers to the thickness of the steel plates that are stamped together to make the stator assembly.

This is a very important variable. The thinner the stator laminations the more efficient the motor.
There are 2 losses that are reduced with making stator laminations thinner.

Loss #1 Eddy Current Losses
Eddy current losses are caused from the magnetic field circulating around something.
The thicker the circle the more the resistance.
Cut the circle down by half and you cut down resistance by a factor of four.
Eddy current loses go up at the square of the thickness.
http://info.ee.surrey.ac.uk/Workshop/advice/coils/power_loss.html#eddy

Loss #2 Hystersis losses
Hystersis losses refer to how much is RETAINED in still in the stator after it is zapped with the charge.
Example of hystersis loss caluculations.
POSITIVE POLE zap it with 100 units of positive power and then turn it off and the stator retains 10 units of positive power.
So to get to a value of 100 units of NEGATIVE POLE
You need to put in 110 units of negative power.


Obviously thinner lamininations = higher cost.
From the research I have done it seems as if the
Sweet Spot of cost vs efficiency = .2mm lamination thickness.
That is what is being used in popular fairly priced Sciorpion RC motors.

Does anyone know what the stator lamination thickness of the Nine Continent motor is?
How hard would it be to get them to make a motor using .2mm thick lams?

 

[masserin]

Am I missing something? It looks like the disk brake cover is on the wrong side of the front weel version of the motor? I think the standard mounting for the caliper is on the left front fork and this is the same side that my ebike-kit hub motor wires exit on.

Would there be a spacing problem mounting a disk cover on the wire exit side of the hub motor?

Do you hub motor covers come already machined to convert older hub motors?

Many thanks

 

[auraslip]

Hey Justin,
I have two quick questions about the new kit:

Is the wheel going to be centered in the frame and not offset 4mm like the old ones?

If it isn't, how does would this effect someone running rim brakes?

thanks

 

[Hyena]

Has anyone found these new motors to be acousticly quieter than the older ones ?
I've never used the older ones but my new one seems quieter with more of an electric train / whirring type sound than the "grunty" sort of sound that the older style (and my GM ones) seem to make.

 

[amberwolf]

I don't have one to compare, but I would guess at least a part of it is the shape of the covers. They may be making the stator differently as well; I didn't really look at any pics showing that.

 

[justin_le]

The number and thickness of winds are an important number.

HOWEVER

Another IMPORTANT and often OVERLOOKED number is the THICKNESS of the STATOR LAMINATIONS.This refers to the thickness of the steel plates that are stamped together to make the stator assembly.

Does anyone know what the stator lamination thickness of the Nine Continent motor is?
How hard would it be to get them to make a motor using .2mm thick lams?

The NC motor laminations are almost exactly 0.5mm thick. Sure the lamination thickness affects eddie current losses, but this mainly comes into play at really high RPMs. In a direct drive hub motor, the electrical RPM is so low that eddy losses in the core are mostly negligible, and hysteresis losses dominate.

Unlike what you suggested, the hysteresis loss from changing the polarity of the stator is not affected by lamination thickness. All that matters is the total volume of steel that is flipping polarity. So I doubt going to a 0.2mm material would change anything in the performance of a Nine Continent hub drive.

-Justin

 

[justin_le]

Hey Justin,
Is the wheel going to be centered in the frame and not offset 4mm like the old ones?

Indeed, the rear motor is now asymmetric, with the spoke flange sitting much closer to the right side cover than the left side cover, and as a result the rim can be centered on the wheel easily without the extensive dishing that the old design required.

The front hub flange is now a little bit offset, so now the front disk motors do require a little bit of dishing, but it's not much.

I've attached some PDF diagrams showing the motor dimensions.

If it isn't, how does would this effect someone running rim brakes?

Assuming Nine Continent doesn't f^#k up their wheel building then they should both run centered and easy to use with rim brakes.

-Justin

 

[boostjuice]

Top effort with the dimensional drawings Justin.

Wow! i think thats the first time iv'e seen you swear on this forum
I can understand your sentiments toward 9 continent Chinese 'engineers'. They recognise where their earlier designs needed improving, but while attempting to remedy them in the newer version, they didn't bother to make best use of spatial constraints. Maybe Rev.3 will finally be optimised :|

 

[Spacey]

Think I might have to try one of these out....

Looks like I'll be ordering all my production parts from you Justin soon enough... you don't supply Headway cell packs do you lol :lol:

 

[Burtie]

Does anybody know which makes/models of disc caliper are narrow enough to work with these new style 9c rear hubs ?

 

[billsy]

Justin

I really fancy one of these new motors for my next build. Can you confirm which winding I will need, to match my current setup which is

48v - 26" - 31mph no pedal

Many thanks

Chris

 

[jmygann]

how many amps ? is this on the flat ? What motor ?

 

[billsy]

how many amps ? is this on the flat ? What motor ?

Hi

The original kit was purchased from a company called xipi.co.uk so not sure what make the parts are. Yes that top speed is on the flat.

The controller is a 40A. The hub is either Golden Motor or an old 9C. Its a good motor but just a bit silly in the front wheel

Cheers

 

[Spacey]

Any idea when these 9C's will be in stock?