HK-4025 12N8P Winding Project

[HeliFX]

gmauro

I'm confused.
This is what my assumption was at the beginning that motor 1 should give me 1100 Kv.
Maybe the Kv meter is not working correctly

By all accounts on paper it should give me 4.5T should give me 1100Kv

Originally Posted by GMAURO

Why? Normally the total kv is not "motor 1 + motor 2"... If you have chek 550 kv for each motor the final kv is 550 (with little approximations).
But is strange 550 kv for 4+5 yy winding.... My 4025 4+5 x 1.4 yy have motor 1 1124 kv, motor 2 1125kv and total 1127

[HeliFX]

GMAURO

stupid mistake on my end.
my kv meter was set wrong since I'm using an electromotive sensor I didn't divide the pole count by 2 and left it at 8.

It should be set to 4 so now my Kv reading are correct.
1130 Kv motor #1

Originally Posted by GMAURO

Why? Normally the total kv is not "motor 1 + motor 2"... If you have chek 550 kv for each motor the final kv is 550 (with little approximations).
But is strange 550 kv for 4+5 yy winding.... My 4025 4+5 x 1.4 yy have motor 1 1124 kv, motor 2 1125kv and total 1127

[GMAURO]

Originally Posted by HeliFX

GMAURO

stupid mistake on my end.
my kv meter was set wrong since I'm using an electromotive sensor I didn't divide the pole count by 2 and left it at 8.

It should be set to 4 so now my Kv reading are correct.
1130 Kv motor #1

no problem, is normal some mistake during the work and new experience. I hope that you don't have understood any offensive intention caused by my bad english....
Ciao mauro

[HeliFX]

take offensive not at all Gmauro
your English in fine

Originally Posted by GMAURO

no problem, is normal some mistake during the work and new experience. I hope that you don't have understood any offensive intention caused by my bad english....
Ciao mauro

[HeliFX]

Wanted to correct my first post regarding my Kv test which was not correct due to wrong pole setting on my Kv motor. Should have set half pole count (4) instead of 8

4.5T short @1.5 mm target 1100
esc: Hobbywing 80A
timing set = 15 degrees
pack: 6S

motor #1 = 1070 Kv
motor #2 = 1068 Kv

now its good

Originally Posted by HeliFX

I finally had the chance to test out the newly re-wounded 4025.

4.5T short @1.5 mm target 1100
esc: Hobbywing 80A
timing set = 15 degrees
pack: 6S

motor #1 = 553 Kv
motor #2 = 551 Kv
total = 1104 Kv

safe to say I'm good to move on to final phase sealing and glue the motor.
unless someone see something I might have missed

[HeliFX]

Final termination of the two motors YY has been completed.
Followed by another 1000V megger test -- passed.
motor once again placed on test bed and all good

Kv with completed YY connection 1070.

one thing to note for those starting out with this motor. A specially when using half turns is make very sure of proper clearance and shim the motor so coils don"t touch casing.
without shims its extremely close fit.
In my case had to add a few these washers for good clearance.

10.3 x 11.8 x 0.22 mm washers

motor ready for final pinning and glue. No M2 screw this time.
will do this on my 700mx.

will post photo later

[Stolla]

MAny motors came to grief because of touching, just make sure you dont need too many shims, i reckon its not good to have the mags and stators not in line, Ralph, please chime in here!

[_Dekker]

HeliFX:
I see your wind does not have equal amount of wire in each slot. Personally I like to have it equal in all because now you "give away" copper space in 2 slots.
Edit: Hmm thinking about it a bit more I believe you actually have less wire length because of 2 slots with "only" 8 wires. So you probably have less resistance. Interesting..
In the pic from post #66: how many wires are there in the slot just before 12 o'clock and 6 o'clock? Looks like 10 but I could be wrong..

Here is an example of a HK4025 (12N8P) 4+5yy 1.6mm wind I did. Gives the same kv as yours. With this wind there is no problem of windings touching the rotor. 9 wires in each slot.



The wire crossovers then look like this, you can still fit it under the stator mount with YY termination:

[ZuvieleTeile]

Very nice Dekker,

@ HeliFX,
since I am going to rewind a 4025 too in the near future, it would be nice to have some (better) pics of your winding, if available. . . from both sides.
In regards to your shims.
From all I was reading in various forums and talks to people who rewound some motors, it is best to shim the can in a way, that it is sitting in its natural position determined by the magnetic force.
Otherwise there might be power loss or maybe heating problems.
I think, Ralph could contribute something here. He has the most experience in playing around with different solutions. . .

[HeliFX]

Hi Dekker,

For starters you can reference this link from Ralph site which demonstrate the same schematic I used only with an extra 1.5T for 5.5 T on each tooth for a lower Kv.

http://www.scorpion.powercroco.de/12N8P4530.html

all slot have 8.5 wires except for 2. one on each motor has an extra half turn.

just before 12 oclock you end up with one extra half turn = 9 that
same with the one just before 6 oclock.
I believe this is the trick in the winding when transitioning to the "nice side" .

if you follow that link I posted and view the forth image you'll notice that extra half turn.

Originally Posted by _Dekker

HeliFX:
I see your wind does not have equal amount of wire in each slot. Personally I like to have it equal in all because now you "give away" copper space in 2 slots.
Edit: Hmm thinking about it a bit more I believe you actually have less wire length because of 2 slots with "only" 8 wires. So you probably have less resistance. Interesting..
In the pic from post #66: how many wires are there in the slot just before 12 o'clock and 6 o'clock? Looks like 10 but I could be wrong..

Here is an example of a HK4025 (12N8P) 4+5yy 1.6mm wind I did. Gives the same kv as yours. With this wind there is no problem of windings touching the rotor. 9 wires in each slot.



The wire crossovers then look like this, you can still fit it under the stator mount with YY termination:

[ZuvieleTeile]

@ HeliFX
Looked at Powerditto's site and see what you mean.

On the shim thing.
Read the text next to the 3rd pic from the bottom. It says what I was referring to above.

[HeliFX]

interesting I was going to post a question regarding shims and how far can the stator move relative to the magnets.

with the scorpion washer alone it is so close that it made me very nervous.
I added 3 washers and this gave good clearance without moving the stator passed the magnets.

I say for sure the stator is still lined up with magnet and not extending pass.
I would say the top of stator is about 2.5 mm lower then the top of the magnet including the 1 mm FG plate height.on stator .

It be great if Ralph can chime explain what one should look for when lining up with themagnet.

When winding my motor I did all I can to try and minimize the height produced with the short transitions. Unavoidable to some degree.

If there's a sweet spot for line up then I don't know how one can tell unless theres a exact measurement that the stator needs to follow between relative to the magnets

Originally Posted by Stolla

MAny motors came to grief because of touching, just make sure you dont need too many shims, i reckon its not good to have the mags and stators not in line, Ralph, please chime in here!

[HeliFX]

ZT,

can you elaborate a little more on this comment.

In regards to your shims.
From all I was reading in various forums and talks to people who rewound some motors, it is best to shim the can in a way, that it is sitting in its natural position determined by the magnetic force.

Originally Posted by ZuvieleTeile

Very nice Dekker,

@ HeliFX,
since I am going to rewind a 4025 too in the near future, it would be nice to have some (better) pics of your winding, if available. . . from both sides.
In regards to your shims.
From all I was reading in various forums and talks to people who rewound some motors, it is best to shim the can in a way, that it is sitting in its natural position determined by the magnetic force.
Otherwise there might be power loss or maybe heating problems.
I think, Ralph could contribute something here. He has the most experience in playing around with different solutions. . .

[ZuvieleTeile]

[QUOTE=HeliFX;3801113]ZT,

"can you elaborate a little more on this comment."

Sure,
when you take all the shims out, slide the mounted stator carefully into the can (With the installed shaft of course) The the stator will assume a position based on the magnetic forces.
There will be some friction between shaft and bearings, so moving the can a little bit back and forth will give you a feel where the magnetic forces are.
Just take the average of those movements and the can sits right where the magnetic forces want to have it.
Now you can measure the gap between the can and the top part of the motor and start shimming away.
It might need several tries to get it almost play-free.

[HeliFX]

ZT,

Ok let me see if I'm understand this correctly.
Is the magnetic force without the shims am l looking for the can to go into a pre-determine position and then keeping that position the say when shiming ?

or

are you referring more in respect to the feel of that magnetic force and maintaining when you shim ?


[quote=ZuvieleTeile;3801174]

Originally Posted by HeliFX

ZT,

"can you elaborate a little more on this comment."

Sure,
when you take all the shims out, slide the mounted stator carefully into the can (With the installed shaft of course) The the stator will assume a position based on the magnetic forces.
There will be some friction between shaft and bearings, so moving the can a little bit back and forth will give you a feel where the magnetic forces are.
Just take the average of those movements and the can sits right where the magnetic forces want to have it.
Now you can measure the gap between the can and the top part of the motor and start shimming away.
It might need several tries to get it almost play-free.

[ZuvieleTeile]

Actually both. . .

Problem is, if there would be no friction when the shaft slides through the bearings in axial direction, then your first point would apply and the stator would be in the perfect position.
But since there is friction, you have to move the can in and out a little bit to see where the middle of the forces is.

[HeliFX]

Dekker,

I've seen your windings for 4025 on other forums. Always very nice work.
Its interesting to see your winding schematic for a 8P motor. I noticed this when I first researching 4025 that you 5454 .. pattern to windings. Unless your 4025 is 10P version

My understanding with 8P ABC schematics is always have equal number of turns on each tooth which Dr.Okon has verbalized to me many times
with that in mind if I did 4T ABC Kv value was too high and 5T Kv was to low from my target Kv 1100.

This is why half turn with short or long transition worked the best cause it maintain equal turns on each tooth plus it mathematically hit my target Kv value of 1100.

hey what do I know I'm still learning and there is a lot to learn

Originally Posted by HeliFX

Hi Dekker,

For starters you can reference this link from Ralph site which demonstrate the same schematic I used only with an extra 1.5T for 5.5 T on each tooth for a lower Kv.

http://www.scorpion.powercroco.de/12N8P4530.html

all slot have 8.5 wires except for 2. one on each motor has an extra half turn.

just before 12 oclock you end up with one extra half turn = 9 that
same with the one just before 6 oclock.
I believe this is the trick in the winding when transitioning to the "nice side" .

if you follow that link I posted and view the forth image you'll notice that extra half turn.

[HeliFX]

sounds tricky.

I wonder if there a more definitive method ?
I think we need the master Dr. Ralph to chime in and set us straight and for confirmation.


ZT,

Is there any literature which you can point too regarding the magnetic system for a brushless motor which describe this in detail.
i like to understand this further.

Originally Posted by ZuvieleTeile

Actually both. . .

Problem is, if there would be no friction when the shaft slides through the bearings in axial direction, then your first point would apply and the stator would be in the perfect position.
But since there is friction, you have to move the can in and out a little bit to see where the middle of the forces is.

[HeliFX]

zt,

just wanted to add something.
If memory service me correctly I do recall when placing the stator into the bell housing it had a natural tendency due magnetic force to push the stator upwards .

with my shims I would need to slightly push on the stator to line-up my c-clip.

so the method you describe makes it tricky.
I realize its difficult to write this in words

Spent sometime messing with shims and pushing the shaft in and out to get it lock in and the same time trying to keep from having wires to close to bell housing.


thanks for feedback, learning something new all the time

[_Dekker]

You really do not need to exactly match the magnetic equilibrium of the rotor position. If it varies plus or minus 0.5mm it still is perfectly fine.