• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Rewind HobbyKing cf2812 motor

jetpackninja

More combat please...
Mentor
#1
I used the information in this video to do my first motor rewind.
The motor seems to be working fine.
Haven't had a chance to flight test it yet.
10 winds of green Radio Shack magnet wire

Edit>If you try this, watch the vid closely. The first two I tried smoked at full throttle.
I rewound the next one more carefully

Stock FC2812
3s 1300 Gensace battery
25-30 ESC
7x6 APC style HobbyKing prop
186.9 peak watts
15.77 peak amps

Custom 10 turn rewind FC2812
3s 1300 Gensace battery
25-30 ESC
7x6 APC style HobbyKing prop
214 peak watts
19.47 peak amps




[video=vimeo;18554942]http://vimeo.com/18554942[/video]

This is the vid I used for the rewinding method:
https://vimeo.com/18554942


And the RC groups thread where most of the info has come from.
https://www.rcgroups.com/forums/show...-Rewind-Thread
 
Last edited:

jetpackninja

More combat please...
Mentor
#3
The original windings on this motor are very fragile. Many times after some hard landings one or more of the lead wires may break.
The original windings are very small many stranded wire that are easier to wind for the manufacturer. Replacing them with a single magnet wire the appropriate size is actually more efficient.

The main purpose here is to take a burnt motor and bring it back to life. 10 winds with the green radio shack wire actually does increase the power a little more than the stock 11 wind motor.
 
#4
Oh...the motor burned. Did you use the same number of windings? I think that some people are modifiing their motors with thicker wire and less windings for greater power (and possibly greater rpm?). I dont think that you can easily make a more efficient motor than the factory one. They are thightly wound and have well ballanced components.
From what I'we learned a burned (3f 400V for home use motor) even if repair rewinded at a clasified service, losses it's efficiency.
It would nice to know what really happens. A benchmark of some sort might be in order.
 

jetpackninja

More combat please...
Mentor
#5
Used one less turn than stock. A little higher KV pulls few more amps and higher kv.
I disagree- I don't think the factory carefully winds these motors at all. (may be different with a high quality motor like a Hacker or a Scorpion) It's all about knocking them out quickly.
Mayhaps I do lose some efficiency but I think not. Don't know if I have a good way to test...
I do get more power, more thrust and more speed with this wind.
Another guy on Rc Groups rewinds these with 9 turns of hi temp rated wire. I don't think the crap wire that I used will handle the 9 turn setup
 

earthsciteach

Moderator
Moderator
#6
Thanks for starting this thread, Ninja. It inspired me to hit Radio Shack on the way home today. I bought some winding wire. Once I'm done surfing the web, I'm puttingthe third phase of windings on one of my burned out motors.
 

jetpackninja

More combat please...
Mentor
#10
Not the windings itself, but the lacquer of the wires burns of and the wires short circuit.
Correct.
And with this motor oftentimes the windings around the stator are undamaged but the wire itself breaks right where it leaves the stator. This can be prevented for the most part by careful routing and securing the wires properly.
 

colorex

Rotor Riot!
Mentor
#11
OK! I just understood a month ago why the BL motors need an ESC! Took me a while to figure it out, now I can explain it if anyone needs it...
 

ananas1301

Crazy flyer/crasher :D
#12
Unless brushed motors, brushless motors need to an ESC for the power to switch the poles so that + get - and - gets +. A brushed one doesn´t need one because it has it in itsel built in on the main shaft.
Advantage of brushless is less resistance --> more efficiency
And you can only change the timing of how often the polarity should switch.

Am I right?

BTT I never winded a motor before and also don´t know how to.

If someones has the nerves to do that he can write a Motor Winding 101?
This would make us bit more independent from rcgroups or so :D
 

colorex

Rotor Riot!
Mentor
#13
Unless brushed motors, brushless motors need to an ESC for the power to switch the poles so that + get - and - gets +. A brushed one doesn´t need one because it has it in itsel built in on the main shaft.
Advantage of brushless is less resistance --> more efficiency
And you can only change the timing of how often the polarity should switch.

Am I right?
Yes. Though brushless motors do not use two poles, they use three. Each pole goes to a magnetic coil. The ESC powers one of the coils at the time.
 

pgerts

Old age member
Mentor
#16
Finally found the time to see the tutorial and it makes me one day try to repair a broken engine.
Here is an example of an enging that stopped in flight. I was not able to see it myself but there is a broken wire thin as a hair. The strand was probaly loose wound from the factory as it got up and shortened to a magnet the second flight.


We do not have any Radio Shack but i can get almost any size motor wire (should be better than RS magnetic wire).

Thank you for the Video tutorial. I have never found it reasonable to rewind the old CD drive motor but when i find an almost new broken HK motor next time --- there will certianly be a rewind.
 

jetpackninja

More combat please...
Mentor
#18
Radio Shack magnet wire is probably not the best to use but it is easily available here and pretty cheap.
I will most likely try to find a wire that has a higher temperature rating to use in the future.
 

earthsciteach

Moderator
Moderator
#19
My first attempt resulted in a fried motor! LOL. It spun, but quickly got REALLY hot and, poof!
I'm tying to get the windings off of the stator. The insulation has melted together into a blob.
The motor is a small, 9 stator, 12 pole. I THINK I had the leads correct.
 
#20
Well I think I partially melted mine. It still works, but I think the lacquer pooled a little. I think this is to blame the brake on the esc, that I enabled a day ago. That is strange because with my setup I'm pulling about 100W on a 250W capable motor. Does anyone have experience with the HK "NTM Prop drive series"?
Another good idea might be to pull apart a classic stepper motor from a printer to get to some magnet wire.