Idiots guide to rewinding Revolt 120 pro

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madin88   100 MW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by madin88 » Jan 07 2017 3:05pm

wouldn't a star-connection be better for efficiency and generally for the controller (easier to drive)?
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Miles   100 GW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Miles » Jan 08 2017 5:50am

Lars,

I have a coil of the wire that you're intending to use.

It measures 2.65mm x 1.35mm including the insulation.

I could send you a piece to play with, if that would help.

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Wheazel   10 kW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Wheazel » Jan 08 2017 5:29pm

Miles wrote:Lars,

I have a coil of the wire that you're intending to use.

It measures 2.65mm x 1.35mm including the insulation.

I could send you a piece to play with, if that would help.
That's a kind and helpful offer!
Have you wound many stators with that type and size of wire?
What tools and procedure would you advice?

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 09 2017 4:30am

@Miles: A piece of the wire would be super, then i can try before i order the full length. I will send a PM with adress.
I would also like to know if you have wound with this wire and how tough it is to work with. Can you recommend it?

On a slightly different note: I've read your inrunner threads, interesting stuff and on a very high level, what is the status on these now?

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Miles   100 GW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Miles » Jan 09 2017 12:02pm

Lars,

PM me your address and I'll put a piece in the post.

I bought some to see if it would be feasible to wind my 36t inrunner with. It wasn't. Inrunners are more tricky to wind than outrunners. They usually require greater manipulation of the wire so, work hardening of the copper is more of an issue. It may be fine to use for your RV 120, the bend radii for this are greater etc.... It would be wise to get a feel for the wire before ordering, though.

With regard to the inrunner design, I have one in construction. The case and rotor are made, the stator lamination stack is made. I'll have more time to work on it again in February.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Miles » Jan 09 2017 12:08pm

Wheazel wrote:Have you wound many stators with that type and size of wire?
What tools and procedure would you advice?
I don't have much winding experience, I'm afraid. The 2:1 ratio wire is definitely easier to work with than square wire, which does its own thing despite your best efforts to keep it from twisting.....

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 11 2017 4:41am

I will make a tool for the opening of the motor, Revolt is recommending a workshop press for the job but i will make a simple screw jig to remove the covers.
See this:
http://www.revolt.org.il/articlepage/ho ... the-motor/

Tips or how-to:s appreciated from those of you that have opened a revolt motor. How did you open/was it difficult/what kind of forces?

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 12 2017 3:56pm

I needed to decide which motor to rewind so i hooked the new motor up. Auto identify worked after two tries (which it never did on my old motor) and the sound of the new motor is a lot better. I think the main issue with the first motor is bad hall placement.

After all: that the controller doesn't find correct combination during auto identify and the manual setting on the adaptto is best on -24 degrees means that the sensors are 24 degrees off. And that also means that hall 1, 2&3 might be off between them by +/-20 something degrees.

I will mount the new motor and rewind my old one. I really hate poor quality! Some things should never be manufactured as they are a waste of resources.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by sn0wchyld » Jan 12 2017 7:25pm

larsb wrote:I needed to decide which motor to rewind so i hooked the new motor up. Auto identify worked after two tries (which it never did on my old motor) and the sound of the new motor is a lot better. I think the main issue with the first motor is bad hall placement.

After all: that the controller doesn't find correct combination during auto identify and the manual setting on the adaptto is best on -24 degrees means that the sensors are 24 degrees off. And that also means that hall 1, 2&3 might be off between them by +/-20 something degrees.

I will mount the new motor and rewind my old one. I really hate poor quality! Some things should never be manufactured as they are a waste of resources.
yep, makes me wonder if i should (at the very lest) replace the halls on my revolt. I do occasionally get cases where the motor starts braking rather than accelerating (ie controler output off by about 180deg!!) which im putting down to bad halls. Rare enough however to not be a big issue. Shame, the general design/size is perfect for ebikes, but the quality isn't even up to china standards... might just get a new motor (LR bigblock looks about right...)

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 15 2017 3:10am

I am tempted to add a flux jacket to the motor, all that leakage flux lowers the torque. How much is difficult to know without doing a FEMM simulation or trying it.
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Re: Idiots guide to rewinding Revolt 120 pro

Post by Karolis » Jan 15 2017 4:25am

What I found with my RV 160 that this leakage is only when motor is assembled. Take the rotor apart from stator and nothing will stick to rotor. Also what i mentioned earlier, this rotor's casing is not even round, It is more like oval shape with more metal on one side than over. it is out of balance in big way.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 15 2017 9:47am

I saw the rotor pictures that you linked. That's a a real shame, Revolt should have scrapped it if they had any quality control. Mine is not that bad.

It's easy to bend some mild steel just to try a flux jacket, measure the kV afterwards. I think i'll do it but not now. I will concentrate on the rewind.

The opening jig is ready, will open motor in the week that comes.
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Re: Idiots guide to rewinding Revolt 120 pro

Post by Wheazel » Jan 16 2017 7:19am

Oh boy I wanna see the results of the rewind now! Or more like yesterday!
I saw that getting 1kg of the wire you are going for cost about 50Euro.

Tempted, even though I don't really have the time at the moment.
I just remember the joy of building my own motors from scrapped cd roms etc.
Some of them became workhorses on small rc planes, and others failed from various design flaws.
The life of a 15yo electronics noob with a passion for rc planes in the late 90s :)

Please weigh the copper that you take off the stator for reference!

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 16 2017 5:15pm

I removed rotor tonight, it was easy with the jig. I am a little surprised at how strong the magnet forces are, after the removal of all mechanical contact it was still needed to continue pulling with the jig to get the rotor completely off.

Windings look shorted and burnt on spots beneath the hall cables.
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Rotor is round and has an even thickness. You can see the modified M10 bolts that was used for pulling in the pic.
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Hall sensor placement is slightly off on one sensor (2nd pic). It's not a lot but i think also that they should be moved closer to the magnets to be switched better. That will require grinding some slots in the stator.
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EDIT:The pictures show a surprise: laminations are 0.5mm, NOT 0.2mm
Last edited by larsb on Jan 23 2017 1:30pm, edited 1 time in total.

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eee291   10 kW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by eee291 » Jan 16 2017 6:51pm

can't wait to see the results!

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Wheazel   10 kW

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Wheazel » Jan 17 2017 3:24pm

Nice pictures, I am curious to what you do at work/hobbies to beat up your fingertips like that :)

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 17 2017 5:03pm

I work in engineering (in an office). The fingers are more hobby related, I had a small accident with some home brew explosives when i was younger, it blew the skin right off three fingers. They haven't been the same ever since :D

I tried to remove shaft tonight but did not succeed. Heated stator to 125 degrees, removed circlip and pushed with a bearing puller but the shaft stayed in place. Bearing glue is visible on the edge of the bearings, i will try to heat with a torch tomorrow.

Bearings could not stand the side load so i will have to replace them. In the end i decided to pull off the rear end cover without the shaft to be able to see the rear windings. That was no problem at all.
Windings are covered with enamel or epoxy and will have to be heated to be able to remove them.
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Re: Idiots guide to rewinding Revolt 120 pro

Post by Ohbse » Jan 17 2017 6:11pm

Good stuff, very interested to see how you get on. The numbers for potential improvements are pretty incredible!

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 19 2017 5:44am

I got the shaft out yesterday, some torching was required and some thinking :D

My shaft is 5/8" instead of 15mm in the drive end to fit kart sprockets. That means the shaft must be pushed to the drive direction instead of towards the other end as is recommended in revolt instruction.

When i realised this it was easy enough to remove the shaft. For anyone attempting to open a revolt motor: i would just remove the covers and leave the shaft in place if bearings don't need replacement if i did it again.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 20 2017 3:40pm

1.5 hours later.. Some teeth could be unwound relatively easy, two or three had wires that needed to be cut to pieces and heated with soldering iron to be able to remove them due to the enamel/epoxy glue.
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Original stator winding:
Copper weight 420g/0.93lbs
Winding length per tooth ~150cm/59" (x5 parallel wires and 12 teeth gives total wire length)
0.8mm/ 20-21 awg wire.
Stator length 45mm.
(Edit: 50.8 / 2" is magnet length, i got these mixed up)

I will measure the slots tomorrow, interesting to see how close i was with my first measurements.

@Miles: your wire turned up today by the way, thanks! I will try a rewind of one tooth with that. The wire is quite stiff so i wonder how precise i can wind it..
Last edited by larsb on Jan 21 2017 6:04am, edited 1 time in total.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by Ohbse » Jan 20 2017 10:39pm

From the looks of the slots compared with your original diagram they might be even larger than you had modeled!

Very interested to hear of your progress, I've heard from many people around here re-winding is pretty hard work.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 21 2017 5:26am

I built a CNC mill some years ago, it has been useful for the bike build :D

My bike is fast but weak so i decided to gear it down more. I drew a 53 tooth sprocket for shimano freehubs and #420 chain and milled it today.
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Looks pretty, doesn't it? :D

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Re: Idiots guide to rewinding Revolt 120 pro

Post by 999zip999 » Jan 21 2017 1:51pm

That is art. If you're not going to use it I would love to hang on my wall.

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Re: Idiots guide to rewinding Revolt 120 pro

Post by larsb » Jan 22 2017 3:53pm

Slots are a bit larger than i measured before.
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The ends are also covered thick and a bit uneven so the steel is further out than the measures show. I will sand a bit with a dremel to get edges smooth and to get rid of residues from the old winding.
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Re: Idiots guide to rewinding Revolt 120 pro

Post by Wheazel » Jan 23 2017 1:51am

Looks like thick endcaps on the the stack. Thats good for avoiding shorts.
Before you try rewinding the thicker wire, I advice you make sure to have some wedges and stuff to push and shape the wire.
You cant pull the arc of a thick wire straight inside the slot. It is a challenge to get the wire flush against the teeth.

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