Wind Toroidal Cores - Tips for 20 Gauge Magnet Wire

[berkeman]

I can see it fine. Man, you've been busy Danger!

 

[Danger]

Not really. I devote a couple of hours a day to it. Probably more today, because W is up in Lloydminster for a wedding and won't be back until tomorrow morning. I like to have something to do while I'm drinking, and there's nothing good on TV today.

 

[berkeman]

Wish I was home with a cold one as well. Unfortunately I'm at work on this sunny Sunday. Got an important deadline that I'll just barely meet. Have one for me!

 

[Danger]

I don't know what you drink, so I had one of everything in the house for you. Pretty much settled into the Canuk and Corona now, because I'm out of Keiths. Saving the Havana Club and Bacardi Breezers for an emergency. The liquor store is at least 100 yards from here, and I don't feel like walking.
Anyhow, here's the slider sketch. Again, it's not to scale and I didn't spend a lot of time trying to 'polish' it.
http://img56.imageshack.us/img56/7863/slider1ju7.jpg
It should be made out of some tough plastic such as nylon with a very 'springy' nature and low friction. Delrin might work. It's made out of a flat strip, and so wants to straighten out. This keeps it spring-loaded against the wire in the hoop. The configuration is designed so that the tension of the wire during the toroid winding phase also tends to expand the diameter. It's width is a snug fit within the channel of the hoop. The 'anchor ring' is there to stick a wire or something through during the loading phase, because the slider has to be restrained from rotating with the hoop. I'm planning to incorporate such a device into the capstan system.
Okay, I'm off to start sketching the aforementioned capstan thingy.

 

[Danger]

Sorry, guys. I took time out to watch a couple of movies and hoist a couple out on the lawn with the neighbours. Anyhow, here's the initial capstan sketch. Since I'm just finishing off beer #18, my input for tonight is probably at an end. Catch you tomorrow.
http://img179.imageshack.us/img179/668/capstan1sq6.jpg

edit: Might screwy, indeed. I'm at work now, and can't see the sketches on this machine either. When I go to ImageShack--My Images, though, they show up fine.

 

[Danger]

Okay, I've got the finalized sketch of the capstan and wire-loading systems finished. Unfortunately, my home 'net' is down so I can't post it until I get it sorted out (or find a working floppy to bring the file to work).

 

[Danger]

Okay, I've got the 'net' going again; it was a router problem. So here's the updated capstan sketch. I've got the toroid staging system worked out as well, but I'm too inebriatated to sketch it up right now.
http://img179.imageshack.us/img179/8200/capstan1ws7.jpg

edit: And once again, I can't see it on a stinkin' PC. It's fine on the Mac and on ImageShack--My Images.

 

[Danger]

So here's a bit of explanation about the capstan system.
First, of course, the drive gears and chain can be replaced by whatever mechanism you want... I just felt like drawing gears. You can use a belt with pulleys, or a worm gear, or even just friction wheels.
The capstans themselves are just rollers from a VCR or something similar, with the outer edges milled down to 1/8" smaller diameter than the centres. That's why I mentioned that it's important to grind the hinge plates down to match the hoop curvature. When the hinge gap hits a roller, the plates take over supporting the hoop on the outer sections of the capstan. You also have to make sure that the latch doesn't protrude past the hoop edge, or else it will cause a bump.
It seems necessary to post a side view of the wire feed system, but I'll go ahead and describe it while I'm here. It's a totally separate unit that bolts into place when you want to load the hoop. The axle is interchangeable to match whatever factory spool you use. The previous sketch of it is actually 'inside-out', in that the spool faces away from the hoop rather than toward it as shown. The only parts that protrude into the hoop area are the top of the feed tube and the slider lock pin. The lock pin goes through the slider anchor loop to prevent the slider from rotating with the hoop during loading. The feed tube guides the wire from the spool to the entrance/exit hole in the slider.
To load the spool, you first open it and place it around the toroid. Then you run the wire from the spool up through the guide tube. Rotate the hoop until the latch is on top. Bolt the feed assembly into place. Thread the wire through the holes in the slider as shown in the slider sketch, then open the hoop again and clamp the free end of the wire into the latch gap. You might have to double it over a couple of times to get a good grip if the gap is too wide. Snip the exposed part off so it won't interfere with the capstans. Insert the slider into the hoop with the anchor ring around the lock pin. Flip your switch to the 'load' position to rotate the ring away from the toroid (clockwise in the sketch). The wire should freely unspool from the loader, through the slider, and into the hoop. When you have as much as you want, or reach the hoop capacity, shut it off. Cut the wire between the spool and the feed tube (to leave a long end) and remove the feed assembly.
I'll go start on the side view now, but I might not have time to finish it before I have to go to work.

edit: Okay, here it is. I didn't bother labelling it.
http://img244.imageshack.us/img244/5773/feedmechanism1td6.jpg

 

[Danger]

I see a couple of mistakes in that sketch; I had to rush it. Anyhow, here's what I figured for the wire guide tube. You need something very strong and rigid, but with low internal friction and that won't scrape the insulation from the wire. (That's why the slider is plastic, as well.) My plan there is to use a section of automotive brake line. Insert a sleeve of something like shrink tubing. You could probably use aquarium hose, but it tends to be a bit sticky. Close off one end and fill it with fine, dry sand or salt. Keep tapping it as you fill, so it packs down. Then bend it to the shape that you want. The sand keeps it from kinking. Dump the sand back out, and there she be.

 

[Danger]

Just out of curiosity, is anyone still following this? If not, I do have other things to occupy my time.

edit: That sounded a bit grumpy, and I didn't mean it that way. I just need to know if it's staying on-track with Jason's requirements and construction abilities.

 

[Danger]

Alright... despite no feedback in 4 days, I'm going ahead with this. (Jason, where the hell are you, you little **********?)
Here's the corrected version of the loader assembly. I discovered today that there was a fatal flaw in the toroid staging system. Took me a couple of hours to completely redesign it. Unfortunately, I can't do up a sketch right now. It's bed time for Danger. I'll catch up with it tomorrow.
http://img170.imageshack.us/img170/1693/feedmechanism1rn3.jpg

 

[Danger]

This is the cam plate for the toroid staging capstan system. Will add the rest to it and label it when I get home.
http://img107.imageshack.us/img107/8739/toroidstage1qu8.jpg

 

[Jdo300]

Hi Danger,

WOW, those drawings look awesome! I've been following the thread and would have replied sooner but I was getting stuck on a couple of the construction details and haven't had the time to explain what I am confused about.

When you were describing the construction of the hoop, I was a little lost about the construction of the different components. There are also a couple of other details that I may need some clarification on. I have a 3D CAD modeling program, Autodesk Inventor6, which I would like to use to render your design. Doing so will help me to better understand what this is actually doing. Plus, if it works well, I could publish a set of DIY plans so that others can build this also. But as soon as I get a chance, I am going to start drawing up the hoop and other parts of the setup to get a better idea of how it works. Unfortunately, despite some of the detailed diagrams, I am still having a bit of trouble seeing how the wire gets from the hoop to the toroid without getting wrapped up on the hoop. But I definitely like the relative simplicity of this. If I can, I may even make a simple controller to run some stepper motors to turn the hoop and toroid :-). Again, thank you very much for your help and I will be keeping a close eye on this thread.

- Jason O

 

[Danger]

Welcome back.
I intend to do up a lot more sketches showing exactly how things go together, and how they'll look in operation. For now, I've just been giving things as they are completed in my head. The only reason that the lack of feedback bothered me was that I didn't know if the design was still following your requirements and construction ability. It actually became a little more 'commercial' than I originally intended, because of your access to metal-working and brazing equipment. Might as well make it as good as it can be, so it'll last a few years with maximum flexibility for different cores and wires.
I'm on a serious burn-out from a very hectic day at work, so mucking about with it some more at home tonight will definitely get me back into a good mood.
Feel free to start modelling before I'm finished. Post your progress here as well. If you deviate from what I have in mind, I'll let you know. Then again, your deviation might turn out to be an improvement, in which case I'll alter my design to incorporate it.

 

[Danger]

Just checking in. I'm working on the toroid staging diagrams, but W hijacked me to go shopping today, then made me go out to party with the neighbours on the lawn. She's still out there, but it's too damned cold for me. Unfortunately, this means that I'm even more exhausted now than I was last night. Might not get much done.
On the bright side, I got my revenge. The first place that she took me, I got 2 pairs of shoes and 3 computer games (including Links LS 2000). The second place, I bought a 512 MB USB thumb drive, an ethernet cable, and DVD's of X-Men, X2, and The Cannonball Run. That'll teach her.

edit: Come to think of it, I'm going to watch one of my movies now. You can wait.

 

[Danger]

Right, then...
I haven't gotten much more sketched up, but I did take the liberty of trying to clarify the previous sketches. They're exactly the same as before, except I added some shading to try and make things more distinctive.
http://img49.imageshack.us/img49/6596/toroidenlarged2in0.jpg

http://img107.imageshack.us/img107/7070/capstan2zu4.jpg

There are a couple more done, but I didn't have time to host them on ImageShack before leaving for work. I'll do it after pool tonight.

 

[Danger]

Here's the final version of the toroid stage.
http://img82.imageshack.us/img82/6996/toroidstage2bd5.jpg

edit: Oops... I seem to have left out an arrow pointing to the capstan, and the label for the top guide plate, but I'm not going to bother fixing it right now.

 

[Danger]

Now for the explanation of the toroid stage...
To start with, I made all 3 capstans simultaneously and equally moveable to make sure that the toroid is always centred regardless of how big it is. One adjustable roller and 2 fixed ones would put it off centre unless it was exactly the right size, and even then the size would change as it was wound. All of them are powered, as well. The narrator in your film clip stressed that as a selling point of their machine, and I can see a point to it. If one roller loses traction for some reason, such as the windings slipping on the core, the others will maintain constant rotation.
The thickness of the cam plate, along with the guide pins and plates and the axle flanges and diaphram washers, is designed to make sure that the axles remain perpendicular to the stage rather than tilting. By the way, I don't know the real term for 'diaphram washers'. I'm referring to the type of retainer used for things like holding parts of a car dashboard together. It looks like a spring-steel washer, except there are radial slots in the inner circumference. When it's forced over a stud that's slightly larger than the hole, the 'fingers' bend outward and grip it. I chose the name because it reminds me of a diaphram-type clutch plate.
One item not yet shown is the idler set. That's a 5th pulley that's mounted on a spring-loaded arm to maintain proper tension on the drive belt when the capstans are moved.
The 'friction plates' are actually anti-friction surfaces of some slippery material similar to that used for the slider. They're to ease the rotation of the toroid and also protect the insulation on the windings.
The '1/2 axle' is a piece of pipe with an arc cut out of one side longitudinally, to match the centre hole in the stage. It's brazed to the bottom of the lower guide plate, then partially inserted into a tight-fitting outer tube to serve as the support/rotation axle for the whole stage as well as the cam plate specifically. (You probably won't need to rotate the stage, but what the hey...) Although not shown in section in the sketch, it goes through the hole in the cam plate and stops short before going through the lower friction plate.
The control tab is just a piece sticking out that you use to rotate the cam plate. It's spring-loaded in the 'close' direction, and you manually over-ride it to insert the toroid.
The top plate/friction plate piece is bonded together, and is used to make the toroid stay put. A weight might be needed on top of it. The guide pins are to keep it in place.

 

[Jdo300]

Hi Danger,

Great Work! Thanks for the detailed drawings you've done. With any luck, I may be able to start on the CAD drawings for it this weekend sometime. By the way, what software program have you been using to draw the diagrams?

- Jason O

 

[Danger]

Hi, Jason. Thanks so much for the compliments. I'm using Illustrator 6 on a G3 Mac. My other G3 has Illustrator 10, which I prefer in a lot of ways, but the monitor is so bad that I can't see the control handles.
My new G3 notebook will be ready next week, and it's got Illustrator CS and Photoshop CS. :!)

By the way, I've noticed a few errors in those sketches. I'm having supper right now, but I'll post corrected versions later. I didn't extend the latch plates to match the rim diameter, and I accidentally drew the 1/2 Axle as larger diameter than the hole in the cam plate. There's also a stray line on the close-up of the latch, and one missing on the end of the loader axle. Since you now know about them, I'll go ahead and start doing up some construction plans and operational sequences first.

edit: I changed my mind. I just realized how tired I am, so I'm going to bed. Maybe tomorrow night.

 

[Jdo300]

No Problem, take your time; and again, thank you for all your help and effort .

 

[Danger]

Okay, Jason... here's the hoop loading sequence for the first turn-and-a-bit. Of course, it continues similarly until you shut it off or run out of wire. (Well, there's another scenario where you put in too much and the slider comes out of the hoop, but we don't want to go there.) You can see from the events why it's necessary that the slider be very springy and slippery. The hoop is essentially rotating the entire mass of accumulated wire around it, while it's forcing the wire to the outer perimeter of the hoop.
As you can see, I grossly distorted the scale for the sake of clarity. For the same reason, I'm posting each step as a large picture instead of trying to fit them all on one page.
http://img479.imageshack.us/img479/3746/hooploading1fx7.jpg
http://img73.imageshack.us/img73/9316/hooploading2mp2.jpg
http://img211.imageshack.us/img211/2508/hooploading3jg5.jpg
http://img473.imageshack.us/img473/6858/hooploading4mi5.jpg
http://img473.imageshack.us/img473/9738/hooploading5jc2.jpg

 

[Danger]

And now for the winding phase. Same deal with the pictures. There are a couple of complications that aren't shown, and I'll deal with them tomorrow. For now, you can see that the slider rotates with the hoop to maintain tension (that's where there's one little glitch), but lags behind in order to let the wire unspool properly.
http://img182.imageshack.us/img182/3903/toroidwinding1nf4.jpg
http://img171.imageshack.us/img171/7404/toroidwinding2fy8.jpg
http://img204.imageshack.us/img204/4668/toroidwinding3sg1.jpg
http://img209.imageshack.us/img209/5300/toroidwinding4ls6.jpg
http://img225.imageshack.us/img225/6960/toroidwinding5bo2.jpg

 

[Danger]

So here's the glitch. Well, not really a glitch; more of a necessary complication. I'll draw the fix tonight when I get home. The essentials are thus:
From the beginning of winding up to the Step 4 point, the slider lags behind the rotation of the hoop in order to play out extra wire to span the diameter of the hoop. Between Step 4 and Step 5, and on until it gets back to the starting point, it has to travel faster than the hoop to reel the excess wire back in. Otherwise there'll be a big loop of loose wire trailing it, which won't go around the toroid in a controlled manner. My solution is that the slider anchor ring is connected to a section of the hoop ahead of it by one or more light springs. The tension of the wire that retards the slider will stretch them. When the tension is removed, they'll pull the slider ahead to it's original relationship with the hoop.

 

[Danger]

Hi, honey... I'm home. Did you miss me?
The slider retard/advance mechanism ended up taking an embarrassingly long time for me to figure out. (Well, it was about 10 minutes over a beer, but getting around to it in the first place was difficult due to extraneous circumstances.) I have the basics down, but not the finer details. It involves magnetic coupling of a guide rail system to the hoop. I'll draw it up for you as soon as I can. It'll be a while, though. Things are kind of loopy around the house right now.

 

[Jdo300]

Hi Danger,

Once again, thanks for all the hard work and effort in this project. After seeing those stills of the machine in operation, I'm just now beginning to get a good idea of how it is working. Though I'm still absolutely lost about the glitch you were talking about. By the way, when the coil is being threaded back onto the toroid, is the entire loop of wire sliding off of the spinning hoop or is it just pulling the wire off of the top of the coil?

Thanks,
Jason O

 

[Danger]

Jason, I'm so sorry that I haven't gotten back to you. I did not realize that you'd posted since my last.
I've been very busy with a bunch of other stuff, so haven't really worked on it. Essentially, though, it uses magnetic coupling between the slider spring anchor and the hoop. That's to provide a friction-slip mechanism. The spring can't be solidly anchored to the hoop, but it also can't be free-wheeling. I'm pretty drunk right now, and am about to become far more so due to a good Celtic band starting at our favourite bar in a couple of hours. This is still something that I'm very interested in.
As for the unreeling, it is pretty much the opposite of the reel on a winch. If your were to invert that winch, so the cable would be peeling off of the inside instead of the outside, then it would be about the same.

 

[RN.Smith2]

Danger and Jason,
Thanks for the exercise that you when through on the toroid winding. Since I too am planning to wind a few Toroidal coil cores for a project of my own. Following this thread was educational in my understanding how the wire is unwound onto the core.

In thinking of a method to build the core winder, I keep thinking of household and or industrial items to use for the parts. I am thinking the metal bands that are on some buckets and small drums could be reshaped for the ring. Since the are already split and have latches, they should be somewhat easy to convert.

Thanks for your thread,
RN.Smith2

 

[Jdo300]

Hello RN.Smith2,

Your most welcome! I still have yet to build my toroidal coil winder but I have definitely not forgotten about the idea! It would be very cool if we could come up with a open-source project that people can build to make them from scratch. I was even thinking about designing one and selling kits for people but I simply haven't had the time to focus on it lately.

It's great to hear that you are intereted in constructing one! I would be very interested to see what you come up with. Also, I found another neat video showing a giant toroidal winding machine. This one also helps me understand the mechanism that makes it work:

http://video.google.com/videoplay?docid=-660662384802328397

- Jason O

 

[Yves]

Hi there !

Just landing here bouncing from links to links contemplating to build my own toroïd winder.
Thanks for all that valuable information.
Things start to be less obscure in my head ! !

Just in case you not already know:
http://waterfuelcell.org/phpBB2/viewtopic.php?t=1034&postdays=0&postorder=asc&&start=0

I've nothing to publish by now, just sucking as much information as I can ;)

Yves.