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Old Mar 26, 2014, 06:04 PM
Jack
USA, ME, Ellsworth
Joined May 2008
16,328 Posts
If you like to build you will like rewinding motors, it is that simple. There are undoubtedly motor rewinding shops in Dubai where you can get wire.

This document gives you an overview of the winding process for a 12N14P motor and it is not that technical or complicated.

http://www.micronradiocontrol.co.uk/.../KH-257D-1.pdf

Jack
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Old Mar 30, 2014, 05:43 AM
Home of Ebbelwoi
Germany, HE, Frankfurt
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Quote:
Originally Posted by franko_ View Post
Hello rewinders,

i know itīs not the CF2805 thread but i have some issues with the 2800KV Motors.
Flighttime with a 3S 2200mAh lipo and cutted 5045 Props is only 5-6 minutes.
Edit: i forgot i to tell.. itīs a quadcopter with ~450g without lipo

My 25c lipos getting very warm and i want to know if there possibilities to have longer flighttime with rewinding and how many turns and winding scheme?
Think they consumed to much power ..

Tried also 2S and 6" props, but itīs not even better regarding flighttime.

If this is normal then i would buy lipos with higher c-rate, but my desire is more efficency.

BR
Frank
Itīs me again ..
Yesterday i disassembled my motors and count the windings.
Three motors have 13 turns delta and one 15 turns, so i calculate 13 turns = 2800kv.
I decide to get more copper in every teeth and rewind my first motor now with 17 turns/0.4mm wire in delta scheme = ~2200KV.
Trust seems good and i rewound all motors ..
Today i flew 3 minutes longer with 6x4 and also trust seems better now.

Nothings hot anymore, iīm happy with these results now...
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Old Mar 31, 2014, 02:15 PM
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KC Flyer's Avatar
Lee's Summit, MO USA
Joined Jan 2001
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Quote:
Originally Posted by franko_ View Post
Itīs me again ..
Yesterday i disassembled my motors and count the windings.
Three motors have 13 turns delta and one 15 turns, so i calculate 13 turns = 2800kv.
I decide to get more copper in every teeth and rewind my first motor now with 17 turns/0.4mm wire in delta scheme = ~2200KV.
Trust seems good and i rewound all motors ..
Today i flew 3 minutes longer with 6x4 and also trust seems better now.

Nothings hot anymore, iīm happy with these results now...
Good to hear that you figured things out.

Sometimes it's as simple as not scraping enough insulation off the end of wire to get a good connection (MD wire has tough insulation) or a short. So it's good practice to check each wire for continuity and that there is no short to the stator before final assembly.
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Old Mar 31, 2014, 04:32 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
near Nijmegen, Netherlands
Joined Feb 2001
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Quote:
Originally Posted by KC Flyer View Post
... Sometimes it's as simple as not scraping enough insulation off the end of wire ...
Sticky: (Re)winding and building motors
Post #1, item #27, removing insulation

Vriendelijke groet Ron
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Old Mar 31, 2014, 04:44 PM
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Quote:
Originally Posted by Ron van Sommeren View Post
Sticky: (Re)winding and building motors
Post #1, item #27, removing insulation

Vriendelijke groet Ron
Good to know. I've been using a lighter most recently and then scraping. The problem with just scraping is that the outer coating of the MD insulation is brown but there seems to be an inner layer that is copper colored. So you basically have to scrape until it shines all around (or until the ohm meter shows continuity). I'll try your suggested method next time:

Removing magnet wire insulation can be tricky, especially when using thin or litze/multistranded wire. Just heat the end of the wire with a soldering iron on an aspirine tablet. Nasty/acrid fumes. Real aspirin, not paracetamol etc., because of acetylsalicylic acid.
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Old Mar 31, 2014, 06:39 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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I just did not have any luck at all with aspirin and various acids and solvents.

So I take the time to scrape and then polish the wire ends bright with pieces of those fingernail files that have a layer of foam under the abrasive strip. They wrap the wire and do a very good job. Then I flux the stripped end and tin it with solder. Any missed spots are clearly seen and you are prepped for best soldering job.

When I consider the time I have in a re-wind, the scraping is only a small donation of a little more time to ensure success.

Jack
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Old Mar 31, 2014, 11:16 PM
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I usually use a propane torch. Burns it off fine. A little sandpaper to clean up the ash, and it's ready to solder.
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Old Apr 01, 2014, 12:51 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
near Nijmegen, Netherlands
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Quote:
Originally Posted by jackerbes View Post
I just did not have any luck at all with aspirin ...
It does not work on all types of coatings, but since it's so simple, best to try aspirin first.

Vriendelijke groeten Ron
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Old Apr 01, 2014, 12:56 PM
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nice thread for re do some older motors. thanks
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Old Apr 01, 2014, 01:29 PM
Home of Ebbelwoi
Germany, HE, Frankfurt
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Quote:
Originally Posted by KC Flyer View Post
Good to hear that you figured things out.

Sometimes it's as simple as not scraping enough insulation off the end of wire to get a good connection (MD wire has tough insulation) or a short. So it's good practice to check each wire for continuity and that there is no short to the stator before final assembly.
Yes, thatīs right ..but sorry i meant my original CF2805 2800KV Motors, which causes a hot lipo and escīs.
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Old Apr 01, 2014, 02:09 PM
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near Nijmegen, Netherlands
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Motors don't cause hot LiPo's and ESC's. Voltage, Kv and prop can cause too high a current for motor, controller and battery.
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Old Apr 01, 2014, 02:47 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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I use only good quality wire, Superior-Essex brand for the most part, and that wire has good coatings on it. So I don't expect the insulation to come off easy. Heck, I don't want it to come off easy!

Some of you guys don't seem to have much patience, and it takes patience to be a good man knitter. You can have good and you can have fast but you don't always get to have both. So when good takes more time, that is the price of it being good.

I had one factory motor burn up on me because they had used a flame to burn the insulation ends off the ends of the wire. That can generate a much longer heat affected zone (HAZ) were the insulation may look OK but it is actually damaged. On the motor that burned up, a bundle of strands that was crossing under a Wye bundle shorted out on the Wye bundle where the insulation was weakened. The insulation on the bundle would have had to have been twice as long to protect the solder joint and the damaged insulation behind it. That was just poor workmanship.

The stripped length does not need to be very long, if the stripped and tinned length is 2-3 times the diameter of the strand, that is more than long enough.

I tin the end, then even up the ends and take a couple of wraps around the bundle, just below the tinned area, with a scrap of wire that still has insulation on it. That holds the wires in contact with each other and it only takes a momentary touch with a small drop of solder to join them. The solder will not stick to the still insulated scrap wire that is holding them together for the soldering.

I always use that Oatey No. 5 flux for that kind of work. It is an aggressive flux and might not be recommended for electrical work but it works wonderfully. Any residue is easily cleaned away with warm water or alcohol on a tooth brush. I have used it for years in this kind of electrical work and never once came back later to find a corroded or weakened solder joint.

Jack
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Old Apr 02, 2014, 12:27 PM
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Lee's Summit, MO USA
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Quote:
Originally Posted by Ron van Sommeren View Post
It does not work on all types of coatings, but since it's so simple, best to try aspirin first.

Vriendelijke groeten Ron
I tried the aspirin method with some MicroDan 22g wire and it did not work. The color of the insulation turned from brown to a copper color but still insulated the wire. The smell was really nasty as the aspirin melted on my workbench

I'll stick with the propane torch/lighter and sandpaper method for now.
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