RC India

I have many motor whose coil got burnt.. I need them to rewind them with new wire. Please someone can tell me which grade wire should be used and how wind brushless motors.. Any outlet or contact that does the same.? I have 4-5 motors whose rewinding has to be done..
Thank you!

here you go

https://www.youtube.com/watch?v=jkxXNDKRH7M (https://www.youtube.com/watch?v=jkxXNDKRH7M)

https://www.youtube.com/watch?v=xBFjH7Yp4eE (https://www.youtube.com/watch?v=xBFjH7Yp4eE)

Thank you. Sir but what about wire which grade wire should be used.? And lubrication? After cleaning the motor there should be some lubrication done on the core for smooth run.?? Where will I get all this stuff.?

The video says the wire gauge.  The rest you can find on Google.

you may find this thread useful

http://www.rcindia.org/electric-power/can-this-bldc-motor-be-repaired/ (http://www.rcindia.org/electric-power/can-this-bldc-motor-be-repaired/)

I have gone through that thread.. But its not clear which grade wire to be use and all other queries ...

Ok.. I was watching the video at low voice couldn't here it.. Does that wire is locally available.??
Does the wire grade changes with change in kv of the motor.?

@aeroempire: wire guage is usually different for different motors. You can get these wire at local motor winding/electrical/electronic shops. They use a guage meter to know the guage of the wire exactly. You need to carry a sample of the wire you want or take up the motor with you.

The Kv rating of the motor depends on a lot of factors like number of magnets, number of poles, number of windings per pole, physical parameters of the motor etc. Wire grade isn't a major factor affecting Kv.

Oh thank you everyone... I have couple of shops available here which winds the transformer coil and even motor coils I'm sure they must be  definitely having this wires.. Just hoping they will even wind the motor for me ;)
Thank you everyone..

But again the question if lubrication I felt some sticky oil like substance present on the magnets! What's that.??

As the magnet and other casing was full if dust , while cleaning it I had noticed that it has some lubrication to expel heat out ...

@aeroempire: If they people would rewind your motors then it would be really great. I asked many of them here but they said: "Ye motor to dekha hi ni aaj tak, itna chota motor" ;D ;D
The oily substance is grease.

Ok ;)

hi,

have gone thru all this and hence offering services.

regds
 

The easy process to measure SWG of a motor winding wire is just wind it side by side over any thing and measure how much turn/cm or inch and get the outer dia of the wire. (Measured by vernier guage or simply diagonal scale and spring compass.)
Just keep in mind the word, the winding should be side by side wire and no gap should present in between the turn.

Then compair with a SWG Table having thick, Medium and thin (insulation thickness) wire table.
http://www.vias.org/eltransformers/lee_electronic_transformers_03_04.html (http://www.vias.org/eltransformers/lee_electronic_transformers_03_04.html)

Hope this may help. Another thing, unwind the winding step by step so that you can place similar winding (New) like that.
Some points to note...
1) The motor was designed for a rated speed (or KV) and all metallurgical aspect, cooling etc. and are optimized by designer. So, better not to modify them.
2) The no of parallel conductor and SWG has been optimized by OEM. So, changing them without remodeling and simulation may damage again (overheat, overspeed, low cooling air flow, heat transfer through bush bearing length and dia, etc. etc.) . Parallel conductors are generally used to reduce skin effect, better coil placement, better cooling. And while rewinding, keep in mind please, no parallel wire cross one another (or twist) so that air pocket may generate that hampers cooling and space in the slot too.
3) You can efficiently wind if and only if you can unwind the burnt coil.

Good luck.

Mr.Kalyan has put the tech in a simple manner as it could be.

But don't get too optimistic with it, as to perfect a motor winding is not as easy as said and learnt. I may be a little discouraging to say it, but you can try it and make small changes one at a time to get until you perfect and try to get the theoretical part aligned to the practical front.

SWG = standard wire guage --> to measure this you should also consider the insulation of the wounded copper, else the guage reading might not be the exact / proper one you had opted to. Again trial and error will help.

Some tools like screw guage will help to get a precise wire guage, but always consider the insulation part. It also helps to get a proper replacement of copper wire with thickness of insulation as needed at minimum. Local insulated copper may not be of good quality, if you buy from an ordinary or unreputed motor repair, and buying at retail is not possible for few grams. They are mostly sold in standard quantity, which could be of surplus of what you actually need. So make a informed decision while shopping these. There is also a bit of insulation enamel varnish to apply cover in cracks developed when new winding is wound.

tip: take some pictures and videos, if possible which will help for any DIY to get thing back right to its original spec.

This might sound a bit too tedious, and that is why there are professional rewinding people who can do it right. :)

Thank you... :)