Can this BLDC motor be repaired?

Started by Swapnil, May 30, 2011, 10:53:04 PM

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sundaram

Please refer to the KH-257-2.pdf file I have sent you. You can try with lesser wattage by using a thinner wire with equal number of winding for all the 12 poles in the manner as shown in this attached sketch.

sundaram

Hey swapnil You were the latest sweepstakes winner!!!!!!. I missed that.

Please send the Motor to me I will rewind and send it back to you. I have sent you my mailing address as PM.  :)

Swapnil

Thanks sir!   ;D
PM'ed you my address.

sundaram

The BLDC Motor arrived three days back.  I was busy with my aquarium (5' x 2' x 1 ΒΌ ') build so could not work on it. The Aquarium is over and beautifully done, Thanks to encouragements, Motivations and ideas from our very helpful VC  :hatsoff:.

The Cir-Clip was removed with a 1mm screw driver tip and the Magnet Cans and the mounting base was separated by pulling out.
First of all, as we all had doubted the winding was not fried but it was actually given a coat of darker coloured enamel/ Varnish after having wound. (It is going to make my day of removing them easily that much more difficult  :banghead:)

Some Preliminary Check before you wind any Brushless more applicable to a BLDC motor from a crashed model or a really over heated and fried Motor.

(a)   Magnetic debris inside motor: There was only a small magnetic Spec inside, which was easily removed and the core and magnets were clean.

(b)   Check Magnets:  All fourteen Magnets were intact and were not loose. However if incase if any magnets are loose you would have to push them tight inside their aluminum slot on the Iron Can and fixed permanent with a very small dab of CA each, Keeping in mind the correct Magnetic polarity this case NSNSNSNSNSNSNS (making sure none of this CA come in contact with the Motor Shaft or flows into the bearings.  I this case since all magnets were fixed tight inside the can, However to make sure it was all given a very small amount of CA. In case there is no slot then fixing them at the correct point at the section is even more difficult and needs to be done with care and proper measurement and setting out.

(c)   Check Motor Shaft:  Check that the Motor Shaft is absolutely straight and easily goes in and comes out of both the bearing. The Shaft was absolutely straight.

(d)   Check bearings:  Check both the Bearings of the motor, that it is freely rotating the can and the shaft, without any rumbling or grumbling. Here in an attempt to remove the cir-clip I think Swapnil had dented one of the outer protective sleeve. However the bearings are running smooth so no worries on that aspect. However this is something to be kept note of while removing the Cir-Clip that right tool is used and the bearing are not damaged.

(e)   Tight fitting of Iron Motor Can on the aluminum body:  In one of my earlier case of rewinding the Iron Can which is press fitted on the aluminum mounting base, it had come loose from the aluminum Mounting base along with magnets  which was required to be again tapped back in with my Goldsmith Hammer and fixed secure with a dab of CA but not a case here.

In spite of all the checks and removing the magnetic debris when the motor was assembled back and especially when the cir-clip was put back it was giving out a minute scratching sound. I had to open the can again.

On closer Inspection I found that,  Swapnil in an attempt the separate the Iron poles and the mounting base with a metallic object had dented the poles corners and the corners of the Poles had deformed and a small projection had come up at four places which was rubbing against the magnets.
However no issues I think I can put it back to shape with my Goldsmith Hammer with light gentle taps or file it back to shape as the kinks are less than half an mm.  :thumbsup:

Photographs of tools used and process follows.

Swapnil

Quote from: sundaramvelar on June 13, 2011, 03:14:38 PM
...
On closer Inspection I found that,  Swapnil in an attempt to separate the Iron poles and the mounting base with a metallic object had dented the pole corners and the corners of the Poles had deformed and a small projection had come up at four places which was rubbing against the magnets.

Photographs of tools used and process follows.

Oh, I'm so crappy with tools :banghead: . Good thing it didn't cause much damage.

Thanks so much for the info+tutorial sir!
Waiting for the pics...

PS: Would love to see pics of your new aquarium too.  ;D 

SunLikeStar

Nice post sundaramvelar, this will be useful for every one {:)}
subscribed & rep++

KALYANPRODHAN

#31
Hi,
I Think this page might be relevent for rewinding.
For rewinding the only thing is to keep in mind that count the turn of each phase in each slot.
Another thing I recomend to use good quality of vernish in coils for good heat dissipation.

http://www.flyelectric.ukgateway.net/motors.htm
http://homepages.enterprise.net/jayjay/cdrom_motors.htm

Thanks.
We have to unite and to prove ourself to make indigenous products as well as marketing / Canvasing them. I'm sure we must achieve success if we try unitedly.

sundaram

Picture of the Aquarium first for Swapnil.

sundaram

Some more Photos

VC

Wow! That is a lovely tank!

Just a few suggestions (if I may) : That tank needs more plants and you know where to get them!  ;D Goldfish and live plants don't go well together. Undergravel filters are not usually used when live plants are thriving in an aquarium.

Btw, in the first and second pics, is it a Moonlight Gourami? They are bloody aggressive creatures and will harass the peaceful Goldfish a lot.

All the best Sandy!
Growing old is mandatory, growing up is optional!

sundaram

Thanks VC. I agree with you these guys have been plucking out the plants from where it has been tied to stone with thread. they have been planted again. Here in shillong nothing is available, so put together with whatever was available. Thanks for the offer.

VC

I should be able to send you some soon. Couldn't trace out the shop in Shillong that i had mentioned earlier. I've planted some Sword Amazons for you and I'm waiting for the cuttings to root. Matter of time now.
Growing old is mandatory, growing up is optional!

Swapnil

Oohhhh....beautiful sir, so beautiful!  (:|~  {:)}  :thumbsup:

I really liked the third one of the ship with a fish (having so many fins) floating just above it. And the stones have been laid out really aesthetically too!

Cool work by Sundaram sir and VC sir.  :hatsoff:

Wonder if one could try putting a gold-fish sized RC submarine in there?  :P ;D ;)
....to play with the fishies!  ;D ;D ;D


.

sundaram

Quote from: Swapnil on June 16, 2011, 07:27:15 AM
Wonder if one could try putting a gold-fish sized RC submarine in there?  :P ;D ;)
....to play with the fishies!

Thanks VC. Thanks Swapnil.

@ Swapnil thats one serious suggestion worth a try. I have to take help of VC for that.

VC

Swapnil, what are you complimenting me for? I haven't done a thing! It is all Sandy's hard work. As far as the sub is concerned :

http://www.dealextreme.com/p/r-c-submarine-2ch-4658

A word of caution : The rotating props can hurt the fish.
Growing old is mandatory, growing up is optional!

Swapnil

Quote from: VC on June 16, 2011, 11:11:01 AM
Swapnil, what are you complimenting me for?...
Quote from: sundaramvelar on June 13, 2011, 03:14:38 PM
... Thanks to encouragements, Motivations and ideas from our very helpful VC  :hatsoff:

VC sir, the compliment was for all the 'help' mentioned by Sandy sir above. I've come to realize that sometimes this sort of help is as much responsible for the final product as the hard work put in.

Swapnil

Quote from: VC on June 16, 2011, 11:11:01 AM
...A word of caution : The rotating props can hurt the fish.

How about a DIY sub with water-pump propulsion instead of propellers?
I made a small 6 cm water-pump (for a boat) using 3v toy motor some 6-7 years ago. It used to work really well. With a little water-proofing we could use it in a mini-sub!

VC sir, have you tried your hands at underwater crafts? After your scratchbuilt hovercrafts ( :bow: ), we would certainly like to learn about DIY subs from you!  :)   

VC

Swapnil, this is exactly what i am looking for! Please share the plans for this water pump. Are you using an impeller mechanism or are you powering a syringe to draw water?

I have been designing a submarine for quite some time now and plan to start work on it soon. Your water pump will prove to be invaluable. Thanks!
Growing old is mandatory, growing up is optional!

Swapnil

It was a centrifugal pump (with impeller mechanism). It was built in 2004, I don't have it anymore to post any pics.
But it's really easy to build and can be completed in less than 20 mins!
The motor I used was a 3V toy-motor (around 1000 RPM without gearbox). We could use a 600 RPM geared motor for greater torque.
I'm currently working on my first scratch-built plane and drawing the plan for the pump would require some time. Is it O.K if I post the plans in evening?

VC

Take your time Buddy. There is no hurry at all. First get on with your plane.
Growing old is mandatory, growing up is optional!

sundaram

#45
Now for the actual rewinding part of the Motor.

First is removing of the existing broken or burnt winding:-

Use a 1mm x 0.25 mm tip to lever out the Circlip holding the Can and the mounting base at the Shaft. Do not use any other screw driver, Knife, nose plier, nails, scissor etc.

Pull out the CAN with the magnets away from the Mounting base with winding Coils.

Clip out the Bullet connectors if it is present. Remove the heat shrink wrap from the Three wires carefully without damaging the strands of the wires.

During the entire process of winding keep the Magnet Can in a separate plastic seal packet safely away from magnetic debries and dust. Further protect the bearings of the Motor also from Dust by not dropping it in one.

sundaram

Some of the Photographs pertaining the the Reply #28 on: June 13, 2011, 03:14:38 PM

is attached please they are

The Aluminium Slot on the mounting base where the Magnets are tightly fitted.

The press fitting of Iron CAN and the AL mounting base.

The Kinks at three places due to attempts by Swapnil to remove the iron core with a metallic object.

sundaram

Removing the winding has to be done exactly in the reverse order of the winding process. Therefore after having removed the Shrink Wraps carefully separate the SIX bunches of Strands of enamel insulated wires i.e. the start and finish ends of the three Phases of the Brushless.

Separate them as shown in photographs carefully, taking care that the strands are not mixed up between different ends. Splice them together as six separate bunches.

Unwinding has to be done exactly in the reverse order. So trace the finish ends of the last Phase which was wounded. which will come off the poles without much effort.

Unwinding has to be done using hand only since winding has also been done with hand which has to be done with repeated soft tugs at the wire bunches around each pole. Do not use Nose pliers unless if it is a totally jammed wires stuck together with Epoxy or enamel. In any case if Pliers are used the enamel wire will break and you will loose the ends for unwinding and then you will have to get into the difficult process of cutting the wires and removing the coils and again trace back the ends.

Unwinding the first Phase ( Last wound ) is going to be little difficult as it will be very tight fit. Once the first phase is unwound then it will be relatively easy to unwound the motor.

Here in this case as suspected earlier, due to the coat of Enamel/ Varnish to the complete winding, right at the first Pole shoe the strands of the Bunch started breaking being stuck in enamel/ Varnish  :banghead:  :banghead:  :banghead:. Half way on the first pole I lost the end completely due to breakage. I in fact doubted whether I will be able to unwind the motor at all. All logic went for a six.  ???

But patience and persistence and delicate handling with Pen knife and 1 mm Sharp tip shaped out of a high tensile metal pin, in this case a metal push rod, played the trick. Strand by strand wire by wire was removed from the four pole of the first phase.

There after it was much easier to tug out inspite of the enamel/ Varnish.

All the phase were removed completely without any damage to the motor, but wire in many pieces.

Ideally it should be removed in three equal lengths of bunches of the strands or a single strand.

The motor was wound in the exact same manner as the recomended winding posted earlier in the thread. It had 10 Turns per pole. the winding was comprising of five strands of the enamel insulated wire for each of the three bunches of the phase.

Swapnil

Wow, that's one handy tutorial. Thanks Sandy sir!  :hatsoff:

Swapnil

VC sir, I'm sure you know the insides of a centrifugal pump very well. The one I made was similar to the water-pumps used in coolers. I made the impeller by sticking rectangular plates on a gel-refill. The plastic cylinder was a 'lime bottle' used in 'paan-shops' (small green coloured one). It's approximately the size of the small motor.
I didn't experiment much with it then, so can't tell the RPM required to generate the required pressure. I used the motor without a gearbox and it worked well. I'm sure you'll make a better, more efficient and powerful design.
Attached pic...