Jul 16, 2011, 06:43 PM Sorry, but they're all toys. United States, WA, Blaine Joined Jun 2009 299 Posts Thanks Ron: Since both motors have the same number of poles and magnets (12 and 14), then why might one have more cogging if the electricals are also the same? And should there be any appreciable difference in performance between the two motors?
 Jul 17, 2011, 11:20 AM Dave North USA, CA, San Jose Joined Apr 2004 5,254 Posts All manner of things can be different between two seemingly identical motors (aside from the wiring errors Ron already mentioned). Here are some other examples: A difference in air gap between the magnets and stator can affect cogging. In particular, an error in the spacing of the magnets can create a harmonic cog. And even more amusing, the actual placement of the turns of wire can have an effect, though very minor -- which means two motors with the same number of turns of the same gauge wire can behave differently simply because one has the wire spaced differently. Just to make it all more infuriating, various minor differences can add and subtract from each other, making each motor quite unique almost no matter what. Dave
Jul 17, 2011, 01:24 PM
homo ludens modellisticus
Netherlands, GE, Nijmegen
Joined Feb 2001
11,907 Posts
Quote:
 Originally Posted by Eric Odle ... Since both motors have the same number of poles and magnets (12 and 14), then why might one have more cogging if the electricals are also the same? And should there be any appreciable difference in performance between the two motors?
The generator effect I mentioned could be taken for cogging. So if you had one of the motors shorted and the other not ...

Vriendelijke groeten Ron
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 Jul 17, 2011, 03:37 PM Sorry, but they're all toys. United States, WA, Blaine Joined Jun 2009 299 Posts Thanks for your insights guys... One more question: I have before me two 2730's with the windings removed. One has a bit more cogging than the other. Could I expect better performance from the motor that has the least cogging, or is it simply more complex than that?
 Jul 17, 2011, 04:39 PM Jack USA, ME, Ellsworth Joined May 2008 18,023 Posts I think you'd have to guess that one of them has better magnets, smaller air gaps at the hammer heads, or something else that is beyond your control in a cheap motors market. Mark them so you can tell them apart, wind them exactly the same, and maybe something conclusive and interesting will emerge in test. Jack
 Jul 18, 2011, 10:18 AM Crash=change of flying medium Boulder, CO Joined May 2002 1,369 Posts To the cogging discussion: I have recently replaced all the stock magnets (which were glued in with typical Chinese "hot glue") with 2mm magnets I bought from Strong RC Motors. I had to slowly sand each magnet to about 1.7mm to make it fit (used sandpaper and custom magnet holder to avoid heating), a lot of work just for the heck of it. I haven't wound this motor yet, but the cogging with tiny air gap and stronger magnets is way higher than in the original motor. Boris
Jul 19, 2011, 11:29 AM
homo ludens modellisticus
Netherlands, GE, Nijmegen
Joined Feb 2001
11,907 Posts
Quote:
 Originally Posted by Eric Odle ... I have before me two 2730's with the windings removed. One has a bit more cogging than the other. Could I expect better performance from the motor that has the least cogging, or is it simply more complex than that?
Cogging, or the lack of it, says nothing about quality, power, magnet strength, power, max.current, torque, Rm, I0, Kv, Kt.

Quote:
 Originally Posted by bluesky123 ... I had to slowly sand each magnet to about 1.7mm to make it fit ...
Make sure the magnets are sealed again (lacquer, resin, nailpolish) otherwise moisture in the air will ruin your magnets.

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 Sep 03, 2011, 09:16 AM Registered User United States, IA, Keosauqua Joined Sep 2010 290 Posts Need info I have a 2712-12 1300kv Blu Wonder from Heads up RC that I need to rewind--(broken lead). I have never rewound a motor so need to be educated starting with removing the old windings. I have taken the motor apart to the extent that the stator with windings,bearing tube and bearings are in one piece, so maybe can skip preschool and start with kindergarten. Initial questions: 1.--How do I remove the old windings? they appear to be glued or epoxied in place. 2.--In order to end up with approximately the same kv as original what size wire an no. of turns should I use? 3.--I have some copper wire that measures about .020 in. dia. that I took from around the picture tube of a color tv set about 40 years ago. Will that work or do I need to order wire from GB? I have read thru the first 50 pages of this forum and have gotten a little understanding but you guys have a language that's still pretty foreign to me at this point. Any suggestions or pointers to tutorials etc. that can help? Thanks for any help you can give Edit--my motor has 12 coil stator and 16 magnets. I'm now thru page 50 of this forum and have thoroughly read the GoBrushless website but still haven't found no of turns, wire gage etc. for 1300kv or so motor. I think I do understand how to wind for a Star type connection however. Bob Last edited by Bob A; Sep 04, 2011 at 08:38 AM. Reason: did more research