# Re-winding a hubmotor

how thick will be the body if you let it 2 stators?
Was it impossible to hold them in place using pins in screw holes or drilling new holes and tightening with bolts?

Using spoke holes?

the body , not sure what you are getting at? if you mean how wide the whole motor will be I am not sure, as it cant be assembled that far yet somewhere around 90mm wide im guessing. I couldnt bolt it together with the spoke holes, they didn't line up well enough due to shoddy machining.

Farfle said:
parabellum said:
...
Is it some kind of known motors you use, or is it something new?

... And it is a known motor, its a magic pie hubmotor

Then this is the famous double-pie (almost a triple-pie)

Not quite the pie-squared, since torque doesn't work that way.

Nice build, by the way!

Nice!!! What is the slot dimension? Gap between toots?

Ok, winding questions. If the stock rpm/v of a magic pie is 7.44 as per this datasheet: http://www.goldenmotor.com/magicpie/MP-performance%20data%2048V.pdf With 6 turns of 8 23ga strands in WYE.

Now, If I make the stator 2x as wide the rpm/v will drop by half, to 3.72. so, to get the rpm/v back up could I rewind it with 3 turns of 16 strands of wire (or an equivalent pair/ of wires), and trade it to delta? Heres my math if you can follow it: 6 t

6 turns is 7.44rpm/v, so 3 turns is 14.88rpm/v

14.88 rpm/v over two (twice as wide) bring it back to 7.44rpm/v which is pretty slow, so ill trade it to delta.

7.44rpm/vx1.7= 12.648rpm/v, slightly faster than the KV of the 5303 (12.12), which would be too fast for a short track. So if I set it up to delta/wye switch, I can get a 7.44/12.64 rpm/v motor, which sounds pretty dang good, the 7.44kv would be a torque monster, and the 12.64 would be a massive top speed at 24s.

Is my math right? or am I missing something?

the slots are rectangular but have rounded corners, so they are aproximately 6.2/6.5mm by 12.5mm. the teeth are 6.5mm wide.

Farfle said:
the slots are rectangular but have rounded corners, so they are aproximately 6.2/6.5mm by 12.5mm. the teeth are 6.5mm wide.

What is the space between tooth caps. It will determine max. wire gauge you can use. look the picture.

its 2.5mm between tooth caps

So it is good for AWG 11, 4 turns, but it will be overkill for sure and PITA as well.

overkill is ok , I have a 250A 100v controller on its way.

ok, here we go,

16 strands of 23ga is 4.01 mm^2
one strand of 11 AWG is 4.17 mm^2
two strands of 13 AWG is 5.26 mm^2 (probably wont fit )
two strands of 14 AWG is 4.16 mm^2
three strands of 16 AWG is 3.93 mm^2

im thinking two strands of 14 gauge for being the easiest to pull, and still get a good copper fill, but ill order dome 13guage first, and see if i can get it to fit

Do not go for to much, I also started on math and dreams but ended with lower AWG fitting far less cross section. Do not forget, good fish paper is thick and takes more then 1mm in each direction. :wink:

hmm, ill order in some 14 to see if I can do a 14x2 and some 16 in case all else fails and I have to do a 16x3. or if if that 14 leaves a lil room to spare ill toss in a 16 with it :lol: .

If I recall correctly from when Luke was winding the H series motor he found all the heavy gauge wire options to really not be feasible- might be able to get a decent wind on a tooth or two, but not the whole motor. Particularly troublesome making the sharp corners without breaking the insulation, etc. He ended up using more strands of lighter wire, more similar to the original wind- for only marginal copper fill improvement.

Good luck! Either way this motor is going to be a BEAST and I can't wait to see it run!

Well, I hope I can get away with the 14guage, going to call around and see if I can get any samples tomorrow.

mmk, have a list of suppliers to call in the morning, and have shot some PMs to members who re-wind motors. If anybody has some practice scraps of 14-18 gauge running around I would love to buy them off ya.

Farfle said:
mmk, have a list of suppliers to call in the morning, and have shot some PMs to members who re-wind motors. If anybody has some practice scraps of 14-18 gauge running around I would love to buy them off ya.
I might have some 14 laying around but shipping time....?

I just discovered your topic Farfle,

Nice project!

Great idea about the DP-420 :wink:

About the winding size, i think like luke about that... the sharp edge of the stator might be a problem with the 14 gauge bending radius... I thgink your will spend like 4x more time than using smaller multi strands...

I'm stil wondering if your two magnet ring rotor are ok.. I mean if they are joined together with the right magnet polarity since they seem to be repulsive.... :| I mean i wonder if they should be atracted instead ( meaning a clocking of one magnet step relative to the other ring...) Anyone idea?
Doc

The magnets have to be put together N/N and S/S so that they act as one magnet. At least thats what I think is correct.

Farfle said:
The magnets have to be put together N/N and S/S so that they act as one magnet. At least thats what I think is correct.
Yup it depends on how the stator is under them but if one stator tooth is going to cover 2 magnets then you have to have the magnets the same just visualize the stator tooth being energized + its going to pull on - magents and push + away. So if you have 2 oposite magents above it it will push one and pull the other and the wheel will not turn!

Doctorbass said:
I'm stil wondering if your two magnet ring rotor are ok.. I mean if they are joined together with the right magnet polarity since they seem to be repulsive.... :| I mean i wonder if they should be atracted instead ( meaning a clocking of one magnet step relative to the other ring...) Anyone idea?
Doc
It is correct if they reject each other, since they are magnetized in perpendicular direction to flat side, sideways they will have same polarity "transition". For Ex back to front, N to S and N to S will reject.

well, im very glad that's correct, I didn't actually put a whole lot of thought into it when i put them together.

Farfle said:
hmm, ill order in some 14 to see if I can do a 14x2 and some 16 in case all else fails and I have to do a 16x3. or if if that 14 leaves a lil room to spare ill toss in a 16 with it :lol: .

Ever heard of Litz wire? You make it up from individually insulated strands of a smaller gauge wire. It has heaps of advantages (magnetically) over using a single wire of a larger gauge. This gets around the problem of the slot not being big enough and will give you a better performing motor.

http://en.wikipedia.org/wiki/Litz_wire

Hmm, thought that litz wire was for coreless designs,

ElectricEd said:
Farfle said:
hmm, ill order in some 14 to see if I can do a 14x2 and some 16 in case all else fails and I have to do a 16x3. or if if that 14 leaves a lil room to spare ill toss in a 16 with it :lol: .

Ever heard of Litz wire? You make it up from individually insulated strands of a smaller gauge wire. It has heaps of advantages (magnetically) over using a single wire of a larger gauge. This gets around the problem of the slot not being big enough and will give you a better performing motor.

http://en.wikipedia.org/wiki/Litz_wire
Sure it will make any sense on AWG 14 at few KHz frequency?

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