Re Winding a motor. (28AWG wire)
 

BIG MISTAKE!!!
I've messed up my reading:oops::oops::oops:
It's a 0,32mm wire so it's 28AWG and not a 22AWG:roll::roll:


Hello,
I've reda the thread on "Winding a motor" and decided to try on one of my RS10 stock motors.
http://www.rccrawler.com/forum/showt...hlight=winding
First they are suposed not rebuildable and indeed it's impossible to change the brushes, but it can be oppened and put to pieces...
http://img825.imageshack.us/img825/2010/modif001.jpg

The non replaceable brushes:
http://img707.imageshack.us/img707/5622/modif003.jpg

They are electricaly spoted to the posts...

And the armature:(well balanced... eaven for a cheap motor)
http://img860.imageshack.us/img860/199/modif002.jpg

Motors are claimed to be 70T but after unwinding the first one I've counted 69T on the 2 first section and 68T on the third...

Now I'm considering as an exercice to rewind those motors and here I need the advices from the "motor gurus":ror:

The stock wire is 0,65mm in diametre or a 22AWG and I have 10,24m of wire for one motor.
Here is a table of sizes in AWG and mm:
http://en.wikipedia.org/wiki/American_wire_gauge

I want more troque, so I need to buy other wires and I was thinking thicker, like 20 or 19AWG, but would it fit inside the amature if I keep 70T??
Or will I still have more torque with only 60T with a 20AWG instead of 70T in 22AWG?

An other thing, the blue stuff gluing the wires is it obligatory and what is it?

Anny help or good advices will be great."thumbsup"

A 70t with 22 awg is gonna make more torque than a 60t with a bigger wire size, however the 60t is gonna make more RPM and more overall power than the 70t. Are you sure its 22 awg though? Sure seems a lot of turns for 22 awg on that armature. We use 22 awg on 45t motors and its a pretty full, certainly would not fit 25 more turns on it. Usually half a gauge is the most you can squeeze on if the arm was filled and even then it doesn't always fit.

Figuring out what you can fit is just using the circular mill (CM) chart. If you know it has X winds of Y size wire.........use the chart and figure out the total CM for the arm (CM x Turns=Total CM). Once you know this number you can use it as a guide (not an abosolute) to figure out wire sizes for lower or higher turn arms.

The blue stuff is balancing epoxy. Looks like it was done on an automated balancer, which has a needle time applicator for the balancing epoxy.

As for the winds being different numbers, this is normal....happens all the time and why guys like me tell people machine wound motors will never work as well as a handwound, this just being one reason.

Later EddieO

@EddieO
Could you give me more info on that CM chart, maybe a link to a table or so...

If I understand you, I could only go for 21AWG instead of 22AWG other than that it would be to thick :???:

http://www.ihiconnectors.com/AWG%20wire%20sizes.htm

22 awg is 642....so 70x642=44940

21 awg is 810....so 70x810=56700

almost 12k additional CM is not very likely....the arm looks decently packed already.

The chart does not list half sizes, but they are easy to figure out.....add the two sizes together for the one in the middle you are trying to figure out, then divide by 2. So, for 21.5........810+642=1452/2=726 for 21.5 awg.

Later EddieO

Unless he is hitting brush saturation, a 60t will produce more torque on the same voltage as opposed to the 70t. It isn't until the amp density gets too much for the brushes that lower turns start to lose torque.

Try a 55t with 21ga. That will be a good start. You may be able to add a bit more depending on how neatly you wind.

Are you planning to balance it after your done?

I've been wanting to try this for awhile and have done a bit of research any info and pics would be appreciated.

@JohnRH:
Thanks for your reading and for point of vue.:mrgreen:

For the balancing part,I'm still not sure...
Those motors are supposed to turn at "low" speed compared to a 45 or less T. I'll try to be clean with my windings...:roll:
And also I dont know exactly with what I could do the balancing.

I dont want to buy to many stuffs for this attempt.

I already will have to buy the wire, so I'm still waiting a bit to be sure of witch AWG size to buy.

In anny case I'll post pictures from the work in progress.;-)

The arm looks pretty similar in size to a 540...if it is, good luck getting 55t of 21 AWG on there....thats a LOT of wire for 55t even if its a small 4mm or so web blank....My GS arms are a 3mm blank, the 45t version is 21 awg and its packed pretty good....certainly am not gonna fit 10 more turns on it.

Are you sure that was 22 awg....seems like a pretty big wire for 70t, even if those webs are super tiny or if the armature is bigger than a 540. I am not familar with the motor itself, so just going off the photos.

As for balancing, the best you can do is a static balance.....which is actually pretty cheap and easy to do. Just get two razor blades, mount them in a block of wood and make sure they are level.....spin the arm on them, noting which spots seem to come to rest at (easier if you mark the segments 1, 2 ,3).....drill a little off that segment at a time until you reach a point where it doesn't really stop at the same spot anymore. Remember you can ALWAYS drill more off, so just a little at a time...

Later EddieO

Remeasure the wire diameter to ensure you got it right. You have a nice set of calipers? I was doing the math based on the wire size given, but Eddie is correct in the wire sizes commonly used on pattern handwounds in the 540 size.

The motor is smaller than 540, it is something like a 400.

As a crummy motor-winding hobbyist, I would say to not worry too much about balancing your first motor. Just be happy when it doesn't fly apart or go up in a puff of smoke. "thumbsup"

The motor is a 380 sized can... and I've used my only one caliper, it never failed me...
I'll try again, should I remove the ceramic coating on the wire to take my mesurement? I didn't thought of that at the first time... :|

keep the coating. Just make sure there is nothing else on the wire.

If thats a 380/400 size motor, I can promise you there is no way it was 22awg and 70t....I just don't think thats physically possible. I think I used 23 awg on my sample 380 motors I did(ended up too big for the MRC), and that was like 15t if memory serves correct.....

Most calipers have a tough time measuring stuff that's super small with any decent accuracy.

My guess, that stuff is small, like 27 awg or even smaller.

Later EddieO

So it's a 28AWG and NOT a 22AWG, I took the wrong part of my calipper to read the mesurement...:oops::oops::oops:

The question is still the same could I go from 28 to 26AWG ? Or would soming burn?

No, wire size has nothing to do with the motor blowing up or wearing faster. Motors only blow up from rewinding as often something was done wrong or the armature was on its last legs anyways.

The only thing really you gotta figure out is what will fit. Now that you know its 28, use the forumla to figure out what other winds and wires sizes you can do. If you plan to stick to a 70t, usually .5 is as much as you get on extra for the same wind....sometimes you can't even do that.

Later EddieO

I have to disagree on this. All of my testing has shown that lower resistance and inductance brushed motors do wear faster. Inrush current is higher, ripple current is higher, amp density increases, and arcing is stronger when fatter wire is used on the same wind. The longest lived motors I sell are the machine wounds, absolutely. The shortest lived are the Fat Packs. It may not be a direct correlation to the wire size, but it is an indirect correlation via the power an armature allows to flow.

Pull more current through a brushed motor and it wears out faster. If this were not the case there wouldn't be such a big difference between the life of a laydown and standup brushed motor.



You could fit a 45t pretty easy with 26ga wire. Maybe even bump it up to 50t. There is certainly some room on the arm.

your testing goes against everything people like Mike Reedy, Jim Dieter, Oscar Jansen, etc ever found............even Fantom never found such findings.

A 7t was the normal motor for onroad, both on carpet and outside. We typically would run a 15.5 awg 7t on a 5mm blank. On some tracks though, that were more open, we could use a 7t 15 awg......not all racers like the big wire 7t though. I've rebuilt 100s of them and never saw any additional wear on them at all. Ask Fantom if they ever saw any additional wear on big wire 7t vs normal wire. The Euros had similar results with their 12t stuff, as they had a 12t mod limit. They would always ask for the most packed arms they could get and it was never reported that there was additional wear over the smaller wire stuff.

Even in the US when we had our 10t limits, no additional wear............1000s of motors rebuilt.

In fact, Brian Kinwald used to run a 7t 4mm blank in mod carpet touring. He was the only person who could make run time with a 4mm blank.......his comms looked same as everyone else on the trinity team.

My advice, get new testing equipment.........

Later EddieO

Ok so here are my calculations:

Stock: 28AWG with 70T
28AWG = 160CM and I have 70T
=> 160 X 70T = 11690 total CM

At 27AWG:
27AWG = 201CM
=> 201 X 58T = 11658 total CM
=> 201 X 59T = 11859 total CM
=> 201 x 60T = 12060 Total CM ( only 370CM added...)

At 26AWG:
26AWG = 254CM
=> 254 X 46T = 11684 total CM
=> 254 X 47T = 11938 total CM
=> 254 X 48T = 12192 Total CM ( only 502CM added...)

So if I understand that thing correctly I can go without any problem for 58T in 27AWG or 46T in 26AWG.
Do you think that I could choose from the second options in both AWG??

And finaly for now, what would be the differences between
58T in 27AWG and
46T in 26AWG? (torque, weels speed, ...)

Keep helping I hope some other people will find that intersting."thumbsup"

In theory you can....remember its a guide, not an absolute. Sometimes the stuff just doesn't fit right, so you gotta go up or down a wire. In the cases, you can just really drop off a turn or two if you have fitting issues. Remember as you wind though, just cause it fits on one segment, doesn't always mean it will work for the whole armature. The wire from each segment can collide with its neighbors, so keep that in mind as you pack it on there.

Later EddieO

You are talking about motors that are already running at brush saturation, so current density cannot be increased. Without an increase in current density the ripple current will not increase either. Crawling motors do not run near this point, so current density does increase with lower armature impedance.

My advice, actually get out and crawl instead of relying on your racing knowledge. Fantom, Jim, Mike, and Oscar don't crawl.


I'm not taking bench testing data to make the conclusions, I am taking input from thousands of customers and my driving team. I found the same thing, but the opinion of one person is a small drop in the pond. The bench data only shows WHY smaller wire motors last longer in crawling.