Tips for neat wire transition between teeth - RC Groups
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Nov 08, 2017, 06:30 PM
Ronaldo Nogueira
ronaldopn's Avatar
Question

Tips for neat wire transition between teeth


Hi folks, do you have any tips of how to transition neatly from one tooth to another when the last turn is close to the edge (not to the root) of the tooth?
I'm winding a big motor SK3 6364 with 8T of 16AWG (dLRK evolution).
The first 7 turns fill the first layer and the 8th turn is the first of the 2nd layer. The problem is that if I pull the wire to the center to start the other tooth it will reduce the space available on the entire slot.
I completed the wind without shorts or any issues but it looks ugly and I'm really not happy with it. I'd like to be able to wind it more neatly.
Ronaldo
Last edited by ronaldopn; Nov 11, 2017 at 03:15 PM.
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Nov 08, 2017, 06:42 PM
just look at it smokin'
z-matrix's Avatar
You can wind one more turn between the tooth heads, and there is space under the stator.


Z
Nov 08, 2017, 06:53 PM
Ronaldo Nogueira
ronaldopn's Avatar
Do you mean doing a half turn and then running the wire under the stator up to the center to start the other tooth? The wire will be loose under the tooth?
Nov 08, 2017, 07:22 PM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by ronaldopn
Do you mean doing a half turn and then running the wire under the stator up to the center to start the other tooth? The wire will be loose under the tooth?
i mean it doesn't matter if it is not inside between teeth until it rubs on the rotor, and you have space below stator where the bell does not rotate nearby...
Nov 08, 2017, 10:40 PM
Jack
jackerbes's Avatar
I would try winding that with two strands of 20 or 19 AWG keeping the two strands side by side, laying flat, and with no twists or crossovers.

And I'd shoot for 5 turns out and 3 turns back. My numbers are based on the wiki AWG page

The 16 AWG has a cross section area of 1.31mm2.

The two strands of 19 AWG would have a tiny bit less cross section area (0.653mm2 each = 1.306mm2) and the 20 AWG cross section is even more less (0.518mm2 , 2 each = 1.036mm2).

16 AWG diameter = 1.291mm
19 AWG diameter = 0.912mm

The advantage of the two strands in parallel would be that it would lay closer to the arms on the turn and the smaller diameter wire would leave a little more room between the turns on adjacent arms at the bottom of the slot.

If you can do it in five turns out (10 strand crossings) on the first layer and three turns coming back on top of those (6 strand crossings) it will bring the last turn closer to the bottom of the slot for when you want to make that transition to the adjacent arm.

Based on the diameters of the 16 AWG you have on there now and the specs on the wiki page I think the 5 turns out and 3 back with two strands in parallel, with either 19 or maybe 20 AWG will fit on your arms.

Jack
Nov 09, 2017, 04:21 PM
Ronaldo Nogueira
ronaldopn's Avatar
Thanks Jack, I have 16, 18, 19, 20 and 21 AWG to choose from. I never wound 2 strands at the same time but I guess it won't be as easy.
Checking TC5 I see that I have a few options which may be easier so here goes another question: is there any restriction to do an LRK wind in a big motor for a 3D plane? I need fast response and I read somewhere dLRK gives a quicker throttle response.
The big advantage with LRK is that I can keep filling the slot with layers of wire without worrying about transitions. I can wind the first layer with thick wire and then continue filling with progressively thinner wires until there is no space left.
Stator is 37x50mm
The ideal kv for me would be 220-230
Ronaldo
Nov 09, 2017, 04:40 PM
Jack
jackerbes's Avatar
Quote:
Originally Posted by ronaldopn
Thanks Jack, I have 16, 18, 19, 20 and 21 AWG to choose from. I never wound 2 strands at the same time but I guess it won't be as easy.
I use either two spools with wire on them or two pre-cut strands long enough to do each phase. And I run the strands through my 3rd hand accessory so there is some drag on the wire as I twist, turn, and roll the turns on. The stator is off the bearing tube and in hand with a dowel handle through it and I just roll up the wire as it comes from the 3rd hand. Not that hard at all.

Quote:
Checking TC5 I see that I have a few options which may be easier so here goes another question: is there any restriction to do an LRK wind in a big motor for a 3D plane? I need fast response and I read somewhere dLRK gives a quicker throttle response.
The big advantage with LRK is that I can keep filling the slot with layers of wire without worrying about transitions. I can wind the first layer with thick wire and then continue filling with progressively thinner wires until there is no space left.
Stator is 37x50mm
The ideal kv for me would be 220-230
Ronaldo
If you have never tried a LRK wind I think you should do that. If there is any disadvantage to it I have not found it yet. There are some thing that will make some motor better suited to dLRK than LRK but the differences in the power output does not seem to be significant at all. For example, most (but not all) dLRK motors have nearly 100% magnet coverage on the inside of the housing (little or no gap between magnets) and the LRK wind is supposedly better when there are bigger gaps between the magnets.

But I see dLRK wound motors with larger gaps all the time and I always wonder if those might not be good LRK wind candidates.

That LRK wind with 9 turns and a Wye termination calls out to me to be tried!

Jack
Nov 09, 2017, 04:57 PM
Ronaldo Nogueira
ronaldopn's Avatar
Quote:
Originally Posted by jackerbes
If you have never tried a LRK wind I think you should do that. If there is any disadvantage to it I have not found it yet.
Yes, I've done a few LRK winds, actually, you were the one who pointed me that scheme
Quote:
Originally Posted by jackerbes
That LRK wind with 9 turns and a Wye termination calls out to me to be tried!
Jack
That is exactly the one I was thinking about
9T LRK wye would give me just the perfect kv. I generated the scheme for LRK wye, is it correct? The winding factor is quite high (0.96593) which I assume is a good thing.

Ronaldo
Nov 09, 2017, 06:56 PM
Jack
jackerbes's Avatar
Yep, that's the scheme. It always looks so simple it scares me. And that housing has some gaps between the magnets and that is a good thing for the LRK wind. All of that looks good, nice thinner arms, plenty of room, etc.

That reminds me a lot of the PR-40 I did a LRK wind on. The initial rewind ran well but died of a short between two of the phases. So I rewound it again with some Tyvek insulation and it has been a good runner ever since.

I should have looked at that first wind closer because it was drawing 4A on the no load test and that is three or four times what it should have been. I think it was destined to fail because of a short...

Your insulation looks good but if you see any bare spot you can put some of that Tyvek over them as you do the first layer of turns.

That PR-40 was sold as a 200g motor, I think it is still right around that weight or just a little lighter. I've never used it real hard, it was used on a glider that needed more weight on the nost and it spun a 15 x 12 folder without even getting warm.

Jack
Nov 09, 2017, 08:21 PM
Ronaldo Nogueira
ronaldopn's Avatar
I already started winding, I believe I should be able to easily wind 2 strands of 16AWG and maybe add a thinner one.
Stator insulation is intact but the wire insulation is so thick that it is almost impossible to damage it even pulling hard as I do to wind with it.
This is by far the easiest motor ever to disassemble and rewind! The bearing tube does not need to be removed and it also incorporates an anti-rotation design. Motor also comes with a really nice cooling fan which is attached to the magnet housing.
It should weight around 700g when finished and I expect to get 3500W with a 19x10 prop.
Ronaldo
Nov 09, 2017, 09:51 PM
Registered User
manuel v's Avatar
A good change to your motor is to replace those small 3 screws with which the motor is held by a larger size.
You have to make new holes in the base.
The reason is that with a blow they break easily.
Last edited by manuel v; Nov 09, 2017 at 10:08 PM.
Nov 10, 2017, 07:36 AM
Jack
jackerbes's Avatar
Those are huge strand bundles, looks like 9 strands or so!

To get a good fill there maybe I'd go with three strands in parallel...

Jack
Nov 10, 2017, 08:39 AM
Ronaldo Nogueira
ronaldopn's Avatar
That picture is from Manuel’s motor, not mine. I don’t know which size either.
My SK3 6364 213kv was originally wound with 13 strands 8T of 27AWG.
Ronaldo
Nov 10, 2017, 09:34 AM
Jack
jackerbes's Avatar
By the wiki page: https://en.wikipedia.org/wiki/American_wire_gauge

27 AWG would be 0.0142" or 0.361mm dia. and area of 0.102mm2

13 strands = 0.0102 x 13 = 0.1326mm2 total surface area

so two strands of about 0.0663 area or three strands of about 0.0442 area would give you the same area

19 AWG = 0.0359" 0.912mm dia. 0.653mm2 area

21 AWG = 0.0285" 0.723mm dia. 0.410mm2 area

I'd probably try one of those and see how the available space looked afterwards.

If you used your caliper and got the dimensions (height, width of the narrow arm part, and length from head to bottom of slot) you could use Turn Calculator 7.2 and get a little more info on the fill. It would be interesting to see how well those predictions work in the real world.

Keeping three strands flat and parallel will be a little more challenging than two strands but if you pull it off you will be eligible for the Hero of Man Knitting medal!

Jack
Nov 11, 2017, 09:02 AM
Ronaldo Nogueira
ronaldopn's Avatar
Finished winding with 2 strands (9T) of 16AWG LRK wye. Some interesting lessons learned:
The wye bundle with 16AWG got so thick that I had to remove the built in cooling fan in order to be able to assemble the motor.
The kv reached (250) was initially a surprise considering TC5 was predicting 229kv but then I realized that it is most likely due to the removed cooling fan. The fan adds friction which obviously lowered the real kv I measured on the original motor (234kv). When I removed the fan after rewinding the reduced friction led to a higher kv value (250kv).

This Turnigy SK3 6364 is officially my favorite 30cc class motor for rewinding. Incredibly easy to disassemble and does not require bearing tube removal or anti-rotation pin. It is like it was made for rewinding

The 16AWG wire is nearly impossible to damage or short no matter how hard I pull the wire. If I wind it again I will probably try a delta termination to get more space and allow me to keep the cooling fan installed.
Rewinding added about 17g of copper.
Ronaldo
Last edited by ronaldopn; Nov 11, 2017 at 09:10 AM.


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