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Old May 18, 2015, 01:30 PM
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Jack
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I rewound three of those for a tricopter and the details are here:

hexTronik DT750 Motor Rewind for Multicopter - http://www.rcgroups.com/forums/showthread.php?t=1892195

I did the Half Parallel dLRK wind on those and did 20 turns with 23 AWG wire. Those finished up with a Kv right around 780 and, as it turned out later, they proved to be good motors for use on either 3S or 4S. Don't worry about the Kv being higher than the original winds, these are more powerful motors and they can handle 10" to 12" props on 3S and 4S with this wind.

The 23 AWG wind was pretty easy to get the turns on with, I tried winding with 22 AWG and found it pretty hard to get the turns to fit on adjacent arms. So I fell back and used 23 for an quicker and easier wind.

Some of the guys have gotten 19 and 20 turns on with 21 AWG with and that would be a job for a really good or really experienced rewinder.

That thread has a lot of info in it on 3S and 4S testing, the motor was actually slightly more efficient on 4S than on 3S, especially so if it is not being flown aggressively.

The guy I did those for did not like the prop savers and changed back to collet type prop adapters. I think if you use more and better bands on these, like three or four Thera-Band prop saver bands, the prop savers can be used. The prop savers make for quick and easy prop changes and will save you from both prop damage and risk of a prop strike breaking motor mounts off and the like.

Jack
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Old May 18, 2015, 05:52 PM
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Quote:
Originally Posted by jackerbes View Post
I rewound three of those for a tricopter and the details are here:

hexTronik DT750 Motor Rewind for Multicopter - http://www.rcgroups.com/forums/showthread.php?t=1892195

Jack
That post is actually what got me headed in this direction. Was hoping to find a "tried and true" number and method that's gone through the testing and the flying. I just need to rewind to repair burned windings close to stock with no risk of letting the magic blue smoke out of anything else.

Looks like 18-20 turns 21awg with Half Parallel DLRK "Y" termination is the most favorable, leaning towards as many turns as you can fit on each arm. Interesting that 4S is more efficient. But 24awg looks easier to work with with

I found this thread: http://www.rcgroups.com/forums/showthread.php?t=523039 that shows dLRK Delta wind with 24 awg. The wire he's using looks much thicker than 24


I think I'm going to do 20T-24awg in DLRK wind with Wye termination. Does this sound like a good "beginner friendly" wind that will give me the results I'm looking for? 25A ESCs, 3S 2200 battery, 10x4.7 (probably going to 10x5.5) props for now.

I'm basically winding, testing, flying, since I don't have a watt meter, a tach, or other goodies you dyed in the wool motor rewinders have. That's why I'm hunting for kind of a known quantity.

Seems like the general rule of thumb regardless of wire gauge is that the lower the turn count, the higher the KV. Higher the turn count, lower the KV. And between 16 and 20 turns on the DT750 is the norm. Wye gives a lower KV and is electrically safer and Delta a higher KV. Is this "generally" correct?
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Old May 18, 2015, 07:20 PM
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Measures of this motor stator 750 DT.
and maximum number of turns with different wire gauge.

You can achieve more turns, but you have a lot of experience and patience to wire it.
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Old May 19, 2015, 10:41 AM
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Jack
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Quote:
Originally Posted by DaMoot View Post
That post is actually what got me headed in this direction. Was hoping to find a "tried and true" number and method that's gone through the testing and the flying. I just need to rewind to repair burned windings close to stock with no risk of letting the magic blue smoke out of anything else.

Looks like 18-20 turns 21awg with Half Parallel DLRK "Y" termination is the most favorable, leaning towards as many turns as you can fit on each arm. Interesting that 4S is more efficient. But 24awg looks easier to work with with
It is the best wind for that motor, there is not doubt about that. As the wire gauge gets larger, the more current the windings can handle. The Kv stays the same for a given turn count regardless of the wire size.

I posted the spreadsheet screenshot in posst #3 on that thread and it has the Kv predictions.

Quote:
I found this thread: http://www.rcgroups.com/forums/showthread.php?t=523039 that shows dLRK Delta wind with 24 awg. The wire he's using looks much thicker than 24
It is hard to tell from a photo, even having two or three sizes in hand it is not that obvious. Look at the sizes on this wiki page and you can see the variation. That is the uncoated wire size in the table:

http://en.wikipedia.org/wiki/American_wire_gauge

I use wire from http://www.techfixx.com/ and he lists the sizes there too. The wire from Tech-Fixx (sold via eBay) is American made wire and about as good as you can get.

Quote:
I think I'm going to do 20T-24awg in DLRK wind with Wye termination. Does this sound like a good "beginner friendly" wind that will give me the results I'm looking for? 25A ESCs, 3S 2200 battery, 10x4.7 (probably going to 10x5.5) props for now.
That will make for a very good beginners wind, 23 was easy to get the turns on with and 24 will be even easier.

Quote:
I'm basically winding, testing, flying, since I don't have a watt meter, a tach, or other goodies you dyed in the wool motor rewinders have. That's why I'm hunting for kind of a known quantity.

Seems like the general rule of thumb regardless of wire gauge is that the lower the turn count, the higher the KV. Higher the turn count, lower the KV. And between 16 and 20 turns on the DT750 is the norm. Wye gives a lower KV and is electrically safer and Delta a higher KV. Is this "generally" correct?
All you need to do is use your fingers and check for heat. When you cannot keep a finger on the windings you are too hot and need to back off a little on the throttle or prop load. We all get a little bit anal about the numbers but you can skip that part...

Jack
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Old May 19, 2015, 11:52 AM
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Quote:
Originally Posted by DaMoot View Post
... Seems like the general rule of thumb regardless of wire gauge is that the lower the turn count, the higher the KV. Higher the turn count, lower the KV. ...
It's more exact than just a rule of thumb.

From
FAQ/sticky: (Re)winding and building motors

Calculating number of winds for desired Kv_new
Kv #winds = constant, for given motor and phase termination (star/delta)
Therefore, for two different winds
#winds_new Kv_new = #winds_old Kv_old
or
#winds_new = #winds_old Kv_old / Kv_new
where Kv_old is either from the factory wind or from a quick'n dirty thin wire 10 (20) testwind and generator test.
Note that parallel strands/winds count as one wind!

Quote:
Originally Posted by DaMoot View Post
... Wye gives a lower Kv and is electrically safer and Delta a higher Kv. ...
Wye will not give you recirculating currents (=losses) in an unbalanced motor, delta configuration/hookup will.
You can get the same motor with delta and wye by winding the delta motor with √3 the number of the wye-winds. Both motors same total amount of copper of course.

Vriendelijke groeten Ron
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Old May 19, 2015, 12:19 PM
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Wonderful, thank you for the help, Jack and Manuel.

These are my first winds from last night. One leg has 18 full wraps and the other has... eh, 'bout 17.5ish... I started playing with the 21awg first 'cause apparently I like doing things to the hard way. :P

I oriented the picture badly but pole 1 is on the left. You can see how much nicer pole 7 came out taking more time to push the windings together with a bit of bamboo and a prop.

While the coating is incredibly easy to scratch, once you get a rhythm down it's not too hard to wind the first legs. I'm sure I'm about to eat my words when I start on the second leg since the bottom of that "V" is already pretty crowded. Taping up everything except the legs being wound definitely helps with the scratching issue. Any other tips or tricks to preventing the varnish from getting scratched? Supposed to be 155c rated polyurethane but is just so darned delicate. This wire is from GC Electronics made in Illinois.

Does the routing look OK with this? I started with a pigtail in the center and wound outwards off of the spool instead of a single long piece of wire and starting in the center. Next time I'll actually come up out of leg one and take the long way around the center hub for neatness sake and to keep the wire more taut. This was more of a full size test run.

EDIT: I just figured out that I had wound this backwards. I had not taken note of Jack's pointing out that the winding should be viewed from the stator end. Or view the image very, very carefully .
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Old May 19, 2015, 12:22 PM
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Quote:
Originally Posted by Ron van Sommeren View Post
It's more exact than just a rule of thumb.

From
FAQ/sticky: (Re)winding and building motors
Thanks. Admittedly I have that thread loaded in a tab, but haven't read it fully. There's just so much information so many different places to absorb. It's dark magic, I tell you! Dark!
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Old May 19, 2015, 05:20 PM
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Jack
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If there is one page that has almost everything you need to know it is the Homebuilt Motors Page

Homebuilt Electric Motors - www.bavaria-direct.co.za

It looks like there is little there but on the various pages there is a wealth of information. I think I could manage all the details of winding with that web page and the wiki awg page.

Your test wind is the perfect way to decide the size the wire that will work for you. As you can see from my added note, what you have there will not work for the 2PdLRK wind because there is not enough room to wind the adjacent arm.

Think in terms of having to use only about half of the available width in the lower part of the slot so you can get the same number of turns on each arm. If you try that with the 24 AWG wire you say you have you should be able to wind a pair of arms.

Jack
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Old May 19, 2015, 05:48 PM
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DaMoot, that looks a tight wind. A good way to practice or test fit is to wind one tooth, skip one, and wind the next. Then see if you can wind the skipped tooth to match. Less frustrating than winding two phases then finding out the last won't fit too. Not that I have ever done such a thing on a 24 tooth stator,
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Old May 19, 2015, 10:46 PM
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Fore new winders, use table post 1653.
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