# Home built series wound motor



## major (Apr 4, 2008)

LloydB said:


> I have some ideals about building my own motor for a ev even though it is popular just to fork out the cash and buy one. I wanted to run my thoughts out to the public for a perspective other than my own on the subject. Here is what I was thinking about doing.
> 
> I was thinking about using sheet metal and make a plate diagram. Then cut a bunch of plates out using that diagram and sand the sides down on the plates to make ever thing nice and neat. Then taking those plates and stacking them to make my rotor. Then spot welding, braze solder what have you to stick all the plates together. Then wind the coils around the rotor.
> 
> ...


Hey LloydB,

Armature lamination thickness is like .018 or .025 inch thick. Core length maybe 5 to 6 inch. Maybe 49 slots. That's like 12,000 little rectangles to cut out while holding dimensions to .001 inch tolerance 

After all that, I doubt you'll be happy with the performance. Better save up the money and buy a motor.

Regards,

major


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## datahar (Sep 6, 2010)

major said:


> Hey LloydB,
> 
> Armature lamination thickness is like .018 or .025 inch thick. Core length maybe 5 to 6 inch. Maybe 49 slots. That's like 12,000 little rectangles to cut out while holding dimensions to .001 inch tolerance
> 
> ...


This was the exact question I was going to ask.
I know you said that performance would not be satisfactory but could you please elaborate on a suitable design? Or point me in the direction of some good web reading on the subject?

I wish to build an EV to trial out a battery system I have been scheming up, and wanted a cheap test subject to try it out on before I go ahead and spend the money on a more advanced system.

Kind Regards


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## Woodsmith (Jun 5, 2008)

From my perspective, I would have to say that if you want to trial a battery system then you would be best off using a standard motor and drivetrain. It reduces the variables in terms of measurable performance.

You might have a great battery system but you could end up with lousey results because the home built motor is rubbish.
I would guess that if you need to ask basic questions on how to make a motor then whatever motor you manage to make will not even compare with any cheap fork lift, golf buggy or treadmill motor. That would not be the best place to start in finding out how good your battery system would be.

I wanted to learn about EVs and stated to scratch build a tractor. It has been great fun but I am also an experienced vehicle builder.
What I learnt in respect to EVs could have been learnt on the bench as I used a golf buggy motor, Curtis controller and LA batteries. Absolutely standard off the shelf parts, standard text book connections, press the loud pedal and it goes.
However, now I can start really learning by changing one variable at a time.
I can build an Open Revolt kit controller and swap out the Curtis to make sure the controller works and to see what differences there are to the Curtis.
When I get some Lithium cells I can compare the performance of them against the LA.
One variable at a time. It is the best way to go tbh.

However, if you have the means to produce a motor well then you could start with this download.
http://greenev.zapto.org/electricvw/Electric_VW/PDF_Books.html
It is a book on electric motors. Not too many pictures and a lot of American standard units maths that confused me as it wasn't in SI units.
I did read it from cover to cover, all 500 or so pages, but that was mainly because I am an insomniac!


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## major (Apr 4, 2008)

datahar said:


> This was the exact question I was going to ask.
> I know you said that performance would not be satisfactory but could you please elaborate on a suitable design? Or point me in the direction of some good web reading on the subject?
> 
> I wish to build an EV to trial out a battery system I have been scheming up, and wanted a cheap test subject to try it out on before I go ahead and spend the money on a more advanced system.
> ...


Hi datahar,

I guess I don't understand. Would you go out and read a few web sites and step into an operating room and perform surgery? Ground up motor design is complex and requires a great deal of solid fundamentals and then more specific knowledge in the area of electromagnetics and energy conversion as well as machinery design and process techniques. But barring spending 4 to 6 years at university and 5 or so in the field, read the web and go for it.

Not trying to be rude here. But realistic. Cedric Lynch did similar to what you suggest and has Agni Motors to claim for it. Maybe it can be done again. By you? I don't know. But I bet chances are slim. You want to do an EV, buy a motor. You want to design motors, forget about the EV for many years.

Just my opinion.

major

ps....Most text on the subject of DC motor magnetic circuit design have been out of publication for 60 years or longer. I had to buy microfilm reprints of them back in the 1970's. Occasionally I see scanned versions of similar text on web sites for sale. They give you a few pages to view for free, but hide the bulk of it. Of course now-a-days, they have magnetic finite element analysis simulation programs. Learn how to use one of those. Good luck.


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## major (Apr 4, 2008)

Woodsmith said:


> However, if you have the means to produce a motor well then you could start with this download.
> http://greenev.zapto.org/electricvw/Electric_VW/PDF_Books.html
> It is a book on electric motors.


Looks like a good general text on electric machinery. One which may have been studied at university. But does not begin to touch on specifics such a DC motor armature winding patterns or magnetic circuit geometry (slot and tooth dimensions).


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## datahar (Sep 6, 2010)

Don't get me wrong I was merely interested in the idea, like you say any simple homemade motor would be rubbish and it is the batteries I am interested in not the motor. However having knowledge of something no matter how basic the level is always a nice thing. I thankfully I will never need to perform surgery, but if in a crisis it was called for it'd certainly find all the information I could before hand, even if all I learned was a scalpel was sharp 

@Woodsmith
Thank you for the link I will give it a read

I will leave my other questions to a new thread and leave this one for LloydB's original question


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## lehjr (Sep 2, 2010)

Just a thought but maybe you could pick up and rebuild a used motor, maybe even from a scrapyard, rather than building your own, if the price is right. The only issue is that the motor may have to be internally re-balanced depending on how much you have to rebuild it. At the very least you could dissect the scrapyard motor just to see how complex it really is and base a home brew design from it. 

As far as building one yourself, there are hobby level diy motor projects around the web, mostly used for model aircrafts, but there have been some that have been used for things like scooters. However, all the ones I've seen are all brushless designs, and most use neodymium magnets, which will lose their magnetism at relatively low temperatures. Even then, they all have some sort of machine shop at their disposal.

small scale:
http://www.rcgroups.com/forums/showthread.php?t=665032

larger scale:
http://hackaday.com/2010/02/18/build-your-own-hub-motor/

I'm sure this is *not* what you're looking to do:
http://hackaday.com/2010/08/23/a-different-take-on-electric-motor-cars/

As to why few if any actually scratch build a brushed motor, I think (and I'm sure someone will correct me on this) that it has to do with the complexity of the whole brush design.


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## LloydB (Aug 28, 2010)

Well I,ve done the university thing. I went to devry 2 years and needed 1 year to finish the engeering degree. They want 45000 for me to finish. Im going to hold off for now. I went to a votec school for 2 years before devry and got a certific in electronics. I also went to UALR for 2 years in little rock and ATU for 2 years in russellville. I also worked worked for a company for a time and worked on the assembly line making ac motors and testing them. But do I feel this makes me an expert. Well no because I never set down and actually designed them or tried to until now. But, my wish was to have something everyone could do not an expert. I still dont believe it is necessary to spend money in excess buying parts because I have a belief that knowledge should be free. But I live in a capitalist society so knowledge is not free sadly to say. I do know one thing about motors and that is the work needs to be precise and it should have a design. Sure, it may not be all that great. I may need to build two or three of them and put them on the same shaft.

On batteries I was thinking about going with a home built sealed aluminium air battery and yes, it would have a generator on board just in case. Its not that I dont think it can work it just takes the right design to work with what a person would work with out of their home. That is why I went with metal plates cut and stacked then welded together. The shaft and bearings should be bought though. If anything at least by the bearings. Some other parts can be bought to like the brushes ect... Not that those would pose to much a problem but the cost for those would not be near as much as buying an entire prebuilt motor. The casing would be made out of sheet metal. Maybe more than one case also welded together to get the thinkness. It would have to withstand certain stresses and heat. I would not use any magnets if mine just coils. Wish me luck. I have some equations to try to go over.


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## Woodsmith (Jun 5, 2008)

I'll wish you luck.

What you propose isn't impossible or beyond reality. I guess if you believe you can then there is nothing worse then not trying.

But there are a lot of experienced folks around here so keep us updated and ask questions.

I would suggest concentrating on one aspect at a time though, motor or batteries until one begins to become well formed and real.


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## major (Apr 4, 2008)

LloydB said:


> Wish me luck. I have some equations to try to go over.


So LloydB,

What you're saying is you don't mind cutting out 12,000 little rectangles? Kool  Bit of advice. Make a knotcher die. Cut out each rectangle with a single stroke exactly the right size.

Glad you realize the limits of human hand workmanship capability and are willing to buy bearings 

Good luck Dude.

major


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