Technique for Maximum Winds per Pole

[LBMiller5]

Happy New Year to everyone in the GoBrushless Community!!!

I started winding my first stator yesterday. I must say it was a little tougher than I thought it would be! I am 43 years old now, and wear glasses for near-sightedness. Not bad mind you, about -2.00 correction, but I can't see worth a darn anymore up close with my glasses on. :( Anything closer than about 16" starts to get blurry. With my glasses off, I can see real well at distances between 8 and 16 inches, but anything closer or farther gets tough to see. I hate to admit it, but I am going to have to break down and get some bi-focals! Now that I have started building motors, I find myself taking my glasses off and putting them back on about 100 times a day, and that is starting to get old! But I digress. I am sure many of you out there can relate to this problem. :wink:

Back to the Motor Theory!

I had torn apart about 20 CD-ROM drives last week, and started looking for parts to experiment with. One of the drives I took apart had the harmonic balancing assembly up inside the can, instead of up on top, inside the CD Spindle. Because of this the can is twice as tall as normal, 13.21mm to be exact, with about 11mm of flat wall on the inside up above the curvature of the front. Here is a Photo of it.

http://innov8tivedesigns.com/rcgroups/Can.jpg

Do you like the neat Digital Calipers? The work in both Inches and Millimeters, allowing you to convert from one scale to the other on the fly. The best part of all is that I picked them up on sale at Harbor Freight for only $15.99! No, that is not a misprint, a pair of digital calipers for only 16 bucks! What a deal!

In my pile of CD-ROM motors I found 2 identical 9-pole stators. They both had an OD of 23.7mm (1mm bigger than the 22.7's on the GoBrushless site), were 4.7mm thick, and had a center hole ID of 8.5mm. I got to thinking that if I put these 2 together it would make a great double-stack, 9.4mm thick, stator for my tall rotor can. The can will accept 10x5x1.5mm magnets, and will give a pole to stator tip gap of 0.20mm. Not bad at all!

I decided to go with 26ga wire on this one and tried to put as many winds on as I could. Because this stator is a little bigger that the stock ones, I was able to get 9 wraps on the first layer. Here is what it looked like. The little wraps of wire around the stator are holding it together until I get the first phase done, then I will cut them off.

http://innov8tivedesigns.com/rcgroups/FirstLayer.jpg


As I progressed, I was able to get 3 layers of wire on each pole before it got too full at the bottom, with 9 wraps per layer for a total of 27 turns per pole. Here is the first phase completed.

http://innov8tivedesigns.com/rcgroups/FirstPhase.jpg


Two more phases and I was finished with my first hand wound rotor. I labeled the wire tails with little stickers, 1A, 2A, and 3A for the starts, and 1B, 2B, and 3B for the ends. Here is the finished stator.

http://innov8tivedesigns.com/rcgroups/ThirdPhase.jpg


As you can see, this one ended up being pretty full, and I was happy with the end result. I am waiting for my magnets to come in right now, so I will have to wait until next week to finish it. Here is the stator sitting next to the rotor can.

http://innov8tivedesigns.com/rcgroups/RotorStator.jpg



Today I wound another stator. This one was a single with an OD of 23.7mm, same as the double stack I had just finished, but it had a larger center hole ID of 9.3mm, and was a little thicker at 4.9mm. I wanted to try a little hotter wind in this one so I used 24ga wire. I was able to get 8 wraps of wire in the first layer and came back with 8 more in the second. At this point I started to worry if I would run into interference with the adjacent pole when I wound the next phase and stopped at 16 turns per pole. I checked the Performance Database, and found motor #47 was closest to what I was doing. It had a 22.7mm Stator with 14 turns of 24ga wire, and the numbers on that one looked pretty good. I figured that mine would have a little lower Kv and a little more torque which was OK by me. Here is a picture of the front of the finished Stator.

http://innov8tivedesigns.com/rcgroups/Front.jpg


And here is a shot of the back.

http://innov8tivedesigns.com/rcgroups/Back.jpg


I was very happy with the way it turned out. The windings were neat and looked good. You can see that I was right about the spacing at the bottom of the poles. The wires almost touch each other, and there is no room left for another wind. However, when I looked up at the top, there is enough room for 2 more layers on each pole. It was at this point that I started thinking about developing a new winding technique that would allow me to put more winds on the poles, while still keeping them neat and orderly.

All of the motors that I have seen wound, including all of the GBv and GBx tutorials, show the windings starting at the bottom of the pole, winding up the pole, and then coming back down. This finishes the second layer back at the bottom of the pole, and with 24ga wire you are done, because if you start winding another layer, it will take up the space for the adjacent pole.

So I thought about the possibility of starting up at the top of the pole. Then you could work down 1 layer, work back up to the top in the second layer, and then come back down at least half-way on a third layer. To test this theory I made a scale drawing using my CAD program. I drew 3 stator poles, and showed how I wound the poles on my stator on the left side of the drawing. Then I drew my proposed new winding method on the right side using the same scale. The drawing is a cross section through the center of the Stator Stack, so each wire shows up as a small circle in cross section. I numbered each of the circles to show the order in which they are wound onto the stator. Here is the drawing.

http://innov8tivedesigns.com/rcgroups/Wirewrap.jpg


As you can see from the above drawing, using this technique, I would be able to get 6 extra winds on the stator for a total of 22, 38% more than before. More wire = More power! At least that is what I have heard, up until you hit the saturation point of the stator.

Well that is my theory on increasing the amount of turns that can be wound onto a stator pole. I welcome any and all comments. Has anyone tried winding this way before? If so, what were the results.

Sometimes we just need to think outside the box!

Till next time.

Lucien

[Q]

Lucien,
move back up after wind 21 and you can get more winds in. If you don't want to go to level 4, you can use smaller wire of course. Going to a double wire wind is another sollution as thinner wire packs better.

[LBMiller5]

Q,

I thought about adding a 4th layer, which could be done, as there is plenty of room left. This would leave the the end of the wind back at the top of the pole, and if you tried to dress it over to the next pole in an ABCABCABC wind, the wire would be in the way for subsequent phases, requiring you to thread the wire under the connecting wires. You could dress it back down to the hub and then go around to the next pole, and bring it back to the top to start the next wind. However, I think that this would get messy real fast!

I have not tried doing a double, triple or quad strand winding yet. (I have only done 2 so far!) To hold my spool of wire when I do my winding, I took an old 50-Pack CD Disc spindle and dropped my roll of wire over the post. Then the spool is free to turn and let wire out as I pull on it. I set it on top of the sub-woofer for my computer speakers, and the volume and tone knobs on top keep it from slipping off. They say a picture is worth a thousand words, so here it is:

http://innov8tivedesigns.com/rcgroups/WireStand.jpg


By doing it this way I do not waste any wire. I just pull it off the spool as I use it, and when I get to the end of a phase I simply cut it off. When you do multiple winds, if you lay them all down together, you have to pre-cut 3-4 pieces of wire, guesstimating how much wire you think you will need, add a couple feet for insurance, and hope you don't run out with 3 turns to go on the last pole. On the other end of the spectrum, if you get done and have 2 feet of wire left, you just wasted 6 or 8 feet of wire! I guess after you wound a few, you could keep a notebook as to how much wire it takes to make a certain number of turns for the different gauges of wire.

The main purpose of this technique was to find a way to deal with a single strand of 24ga wire or with 22ga wire if you wanted to go really big!

Does anybody else have any experience with alternate winding techniques?

Lucien

[DadHav]

Hi Lucien, Man are you ever a technical guy. It's always fun to read your posts. I just happened to see your question about winding techniques. Maybe I can add one that helps. I like to wind 3 or 4 strands of #30 wire on most of my motors. I love the thinner wire because it's just easier for me to fill the legs evenly and you don't have to pull as hard to get the wire to lay in there. The last motor I did like this, for what it might be worth:
-I figured out how much wire I would need for each phase by winding some string around one phase then adding about 6 inches.
-I set up two magnets on the metal frame of my work bench to that distance. These are like the kind that hold cabinet doors shut.
-Stick the end of the wire to wind under the first magnet and wind the three or four lengths around the set of magnets to get three wires the length you need.
-Twist one end of the wire and put a heavy duty spring paper clip on it.
-loosen the other end, scrap the enamle off the wire, twist and solder them.
-Take the soldered end and tape it to the bushing holder at the phase one possition, and start your winding.
-Hang the wire over something like a chair back so the spring clip can keep your windings with a little tension.
-When finished with the phase. Cut the wires to the length you need. twist and solder them.
-I'm winding Delta on this one so I size my phase two wires.
-Now this time I take the twisted soldered start end of phase two and solder it to the first phase as should be done for Delta.
-The same procedure as above for with the last phase.
-You finish by soldering the last phase to the first as per Delta.
This really lets you have a neet job. I would like to just have three or four reals of wire to pull from, but I don't know if that would be practical.
Oh Ya, I guide the wires as I wind with my thumb and pointing finger, while turning the stator asembly in circles to take the wire. Did you ever hear the lightbulb joke? Never mind. I also have a propeller blade sanded thin enough to push the wires a little if needed between the legs.
If you go to my galary, I think I have a picture of a stator ready for winding. Numbering helps.
I hope this might help spark an idea or two.
Man, I wish these forums had a spel checker.
C YA

[Pipistrelli]

Lucien,

I have often wondered the best way to get 3 neat layers and I also wondered about starting at the end of the tooth because this is where the most space is.

I have considered using the technique you have used because it looks like it is easy to start, but because the wire of each phase will cross over other phase teeth (and not at the hub), does this mean that you have to wind a single tooth on all the phases, then the next tooth for each phase and the final tooth for each phase?

Also going from one tooth to another and starting at the outside will mean the wire will be on the outside of the stator, so you will need to thread the wire through for the remaining phases!

I know this is confusing, but I hope you understand what I mean! Can you draw another diagram to show how the teeth will be connected please!

[DadHav]

Good Morning Pip, I tried an experiment once with #26 wire: At the start of the wind, I taped the wire to the bushing and then fixed the wire up against the leg of the stator so that the wire ended up at the top. I used wire tie thread to secure the wire, then wraped my first wind down towards the bushing covering over the wire going up the leg. It's a bit of a trick trying to get ready for the winds, but the motor ran real good. I find that winding three or four strands at a time allows you to get to the top of the leg without taking up much room, but here's the thing: I'm winding three at a time and the winds are random as opposed to being in perfectly side by side like little soldiers. I don't know if this is acceptable, but my motors have been running with real good specs.
Have a nice week end.
John

[DadHav]

Just noticed that the time shown for the posting is off by about 11 hours.
Something Wrong?

[ScubaSteve]

Seems no matter how many times I adjust the "master" time for this forum, the change never sticks... :oops: :roll:

[DadHav]

Not a big problem Steve, It's just when you're my age, you'd rather see the time going slow instead of fast. Have a nice day. By the way. I made a single size LRK from your 25 mm stators. All twelve legs wound, using 13 turns three strands. Man, what a sweet running motor. Thanks for the supplies. I'll put a picture in my gallary later.
John

[latrans]

LBMILLER5,

I just saw this thread. Funny I've built some of the exact same motors you have, I even have one of those double cans and did the exact same thing you did. Just wondering what kind of performance you got from your double 23.7 and single 23.7?

Latrans