I am building a Magneto, need help with the coils...

[twilightinsanity]

   I am thinking about probably using 2 inch cylindrical coils with a 1 inch core and I'm not sure how high to make these coils (length of cylinder) because I don't know how far the magnetic feild extends from the magnets since I dont have them yet. I have seen a few places that sell them, and 1 inch by 1/4 inch seems to be a common size, I supposed I'll use those, unless a longer magnet is recommended...  Then again, I could just as easily use a 1x1x3 inch square magnet, and make my coils pie shaped to fit those instead. I may use this option because of the larger gauss ratings and the fact that they would allow for more hardware in the same space, with equal work on my part...
   I live in the south so I won't be able to get black sand from the roadside due to the large amounts of rust and the like which is probably comprised of old cars. People are poor around here, and theres no state inspection of any kind (Florida sucks, you come to visit on vacation, your car gets rusty, and you leave with lung cancer on probation, and come back in six months on violation and die because the state medical practitioners have to charge double to pay thier insurance. Sorry, that wasnt a rant, it just sounded like it!)
   But theres a gold and gem mine nearby, they sell bags of the stuff for tourists to go panning, so I can go there and get some sand. I hope it works as well as it's said to.
   I'm planning on a 4 foot dual rotor setup, with the coils stationary in the middle. I'm thinking about running continuous coils, in two rings around the periphery of the stator, each ring will produce single phase AC, and they will be arranged 180* out of phase, which will give me two phase AC out. Hopefully I can make the two separate rings of equal proportions so that they create the same results - I'm sure the inner ring will be a little weaker, but hopefully it will be only a few percent...  Theoretically, if I can manage my Rpm's right, I can make 60Hz AC, or close enough to be usefull... But if not then I can build a simple rectifier, and get some stupid batteries. Maybe putting the wild AC into correct phase would be cheaper though, and more cost effective in the long run...
   I will probably use a 16" bicycle wheel for the hub assembly, and ferrous plates or laminate behind the magnets. I could also coat the plate the magnets will sit on with black sand mixture, or just use the black sand by itself, but I'm not sure this would have the same effect as a metal ring behind them. It would certainly be easier.
  Seems like the most intricate part of this whole approach is in getting the magnets close to the coils. Obviously, the larger the wheel the more difficult this is. Even if I could find a truly flat piece of plywood, it would warp in no time without a solid frame, and I don't have room for any kind of framework, even if it could be easily balanced. So I guess that means I'l have to fabricate something flat. Easier said than done. I just thought of a decent idea! I can goto the local thrift store and buy a really ugly table. Then I can coat it with wax and make a fiberglass rotor on top of pre-placed magnets. That way the magnets will be fixed permanently where theyre supposed to be (unless I want to retrieve them). Oh man, that means I'll be itchy for a week! I hate fiberglass, it's like synthetic chiggers (red bugs).  Don't suppose theres a better way to make a flat rotor? I could mix resin and black sand and make the rotor body out of that....
   I was thinking about making the stator out of something that is slotted or notched, so that I can remove coils without dismantling the thing, that way I can fine tune anything that needs it, and I'm sure things will need done differently before I'm settled on any one coil configuration. I was also considering the possibility of making a DC system on a separate interchangeable rotor. Maybe use a set of toroidal coils, made from black sand... Say, would that work better you think? Better than the usual way? Probably not because theyd do it that way if it was, but then Tesla's high freq AC was better (it didnt shock people at least) and they dont use that at all, so...

   Say, I'm not trying to pry, and its way off subject, but what does your solar powerd water generator do? If you could affix it to a standard solar hot water heater then it would be great. Actually, it's great anyway since its free. The Micro-Tide Generator. I'm curious...

[fleebell]

Ok, hmmm I've got a few suggestions to make your life easier. If your going to use a 4" diameter rotor use a piece of wood 1/2 - 3/4 max thick and cut out holes in the wood for the coils to fit into. (don't forget slots for the wires to exit from)  fiberglass them in place and leave the leads outside so you can modify your wiring.

Your coils should be big enough that the magnet can fit completely inside the coil whether they are round or oval and try to keep them as thin as possible - preferably <1/2" but no more than 3/4"  The entire stator needs to be kept as thin as possible and still be stiff.

  Make sure you use enough coils and magnets so you can wire them three phase later on. (I can almost bet you will not like trying to keep it at 60 cycles by controlling the wheel rpm for very long and will resort to the battery setup eventually.).
    Use more stiff wooden wheels for the rotor(s).  I agree, a recycled presswood table probably would probably work better than plywood but make sure you seal it extremely well.)  Again cut holes for the magnets leaving maybe a 1/4 " of face sticking out. If using two rotors cut strips of sheet metal to fit behind the magnets (at least 4 layers ) and fit a curve all the way around the wheel behind the magnets.(it should be wider than the magnets) Epoxy or resin everything in place (screw the sheet metal to the backsides of the wheel). If only one rotor the black sand in the coils should do it but don't put any in the coils if you are using two rotors.

   I don't think your going to have enough torque to do two circles but if you at least cut the holes for them the first time you can always go back and add them later if needed.  If you are going to use a bike hub for it I suggest you use a 20" one instead of the 16". Most 16" hubs are crap and you will at least stand a chance of getting something decent in the 20" size

   An alternative would be to use pipe with flanges as the hubs as it would be much stronger and give you something to bolt the rotors to at the same time. Pick a pipe size that will slide over your axle, shim it straight and just pin it to it. Then use regular bearings that mount to a frame with the axle. That would make it easier to hook up your driver to it.  (of just make a big Hugh P style using car wheel parts, that would be the strongest setup and best too for an alternator this big - imo)

Those small bits of rust won't hurt anything and will work ok if you screen it to get out any large chunks.   That is what I have been using for black sand... I live in Wilmington NC just a few miles from the ocean... same problem with car rust, my neighborhood is about 70 years old and there is plenty of it on the side of the road.   Put the fine stuff in a old frying pan with a little water and stir fry it until it turns black and is totally dry. That will anneal it and put a protective oxide coating on the individual pieces.
  It will work ok to use as black sand then. (at least it does for me)

[twilightinsanity]

   Hey man, your suggestion of using a frying pan was resourcefull, and I've never heard of annealing things quite that way before - and I'm a glassblower, so I know about annealing! I suppose I should go offer my services in the Moray Device forum, but frankly I'm afraid somebody will want me to do vacuum tubes full of  radioactive material and I don't wanna lose sleep because my eyelids are glowing... 
   Anyway, I was thinking about the process youre using to aneal the iron particles, and it seems sound (though I dunno how hot the iron has to get to create the proper results, I thought it had to get hotter than a water bath on a stove would allow, oil would seem to be a better choice, but maybe I'm thinking about tempering...)
   I knew a Viet Nam Vet, gone now, who showed me a nice trick once. He said that during the war the rain made everything get rusty, and when your life is depending on your gear you learn to keep the rust at bay. He showed me an old case xx pocket knife that was very rusty (you know how black bladed knives rust) He dipped the blade, rust flakes and all, into a jar of plain yellow mustard and laid it aside. The next day the mustard had turned black, and rubbery. When I peeled it off the blade was shiny and black, without a hint of rust. The copper knife body turned a sort of pink color though, so the acids in mustard arent good for making copper pretty. Mustard works as wel as ospho from what i've seen, and its cheaper and safer, and easier to come by as well. One good trick deserves another, so I thought I'd tell you this one in return for the iron filings in a pan one... 
   Umm, I think the iron filings will retain an EMF feild longer than the black sand, I'm not sure but it may even defeat the purpose. What I mean is that if the filings hold magnetism, then they would induce magnetism in the black sand as well, for the length of time the iron retains it's magnetism. I'm in georgia, and they have a lot of mines around here, I bet they do on your side of the mountains as well. Just saying that maybe theres a simpler and contaminant free way to get sand, rather than using a magnet.
   So, since I'm using two rotors, I won't need the cores? Do you think they'd make it less efficient, or harder to turn, or just wont do any good with the extra magnet on the back of the coils?
   I think your suggestion of car hubs would be a good idea, but I don't wanna overkill either, bigger parts mean more bearing drag... Then again the more I think about it the better the flanged pipe idea sounds to me. I guess I'll figure it out soon enough, I plan to start on this thing soon, my magnets are not ordered yet, because of size considerations, but when they get here I hope to have everything else about done.
   I have a strong feeling youre right about my torque not being enough to do two rows, (maybe even one!) so I think I will make a stator that has notches cut in it so that I can remove and replace coils very easily. That way I can try different wiring configurations and coil types. I wish I could think of a very simple way to make the rotors adjustable for width as well, but so far all I can come up with is washers. I'll make it so that the stator is 1/2 In thick, and separated from the rotors by as little space as possible, hopefully I can make everything flat enough to get 1/8 or even 1/16 air gap between the parts.

   Slowly but surely, it's coming together. With an interchangeable design I won't have to worry about exacting coil specifications yet, which makes the whole thing a less cumbersome idea. I may also make another wheel or two to add to my overall torque ratio. I can't see how to get more Rpm's without a vacuum tube the size of a storage unit, and then I'd only get about ten or twenty percent, so my object must be for more torque, which is easily attainable...

[fleebell]

Thanks, I've never heard of the mustard trick before, I'm going to try that.  Don't use oil in the pan, the water is there because it has to do with the chemical reaction that that blackens the iron particles. (alpha hematite into gamma hematite)(sp?). Not really needed but helps keep them from rusting in the epoxy. They will work ok, it you use fine stuff as it's pretty much the same thing as black sand although you will not need it if you use two rotors, it will just absorb some of the field and you don't want that as you have the other magnetic field to use instead.
Yes, car hubs do have more resistance to turning but you can take out most of the old grease and loosen the preload on the bearings and they will spin pretty freely and that will make a big difference, light oil would work just as well as the bearings will never be stressed in this usage.

I prefer using the pipe fittings as you can modify stuff a lot easier that way if you need to. (I have a lathe and learned to do aluminum casting a couple of years ago- it makes building things much easier when you can make your own parts if needed)

[twilightinsanity]

   Well, I've gathered enough information (thanks for the help!) to begin making everything. It will be awhile before I have all the parts, and I really can't begin untill I have measurements for everything. I am going to make one continuous row of air-core coils, with two rotors. I'll either use circular 2" coils and circular 1" magnets, or if I can afford it I will overkill with 1"x1"x3" rectangular magnets and oval/pie shaped air- core coils. I'l go with thirty windings first, and see how that works. I'll make slots in the stator so that I can change out coils easily, and rewire different patterns as well. Fiberglass is probably what the stator and rotors will end up being made of, minus whatever the metal backing for the magnets I can find. The hubs will probably be made from whatever light automotive hubs I can find, I'll need two, so maybe I can get a whole rear axel from a FWD vehicle...
   If this dose'nt work it will be because of low torque, but if I have to I can make more torque as needed. The 4' wheel size should compensate for the lower Rpm's. Hopefully it won't look too ridiculous when I'm done. 
   I'm not in posession of a decent digital camera, and the magneto is basically the same as the one it's modeled after except the diameter is doubled and the number of magnets is increased, the number of coils is larger too, but I dont know if it's doubled or tripled since I think they only used 15 and I'l need 50+ (though maybe theyll be smaller ones).

   That was a most useful link you sent, and I'll repost the specific windmill model I found and will use here:
   http://www.otherpower.com/20page1.html

   So, regardless of the actual efficiency and workability of my idea (and more importantly, my workmanship) I am guaranteed to be able to make at least 100 watts of constant wild AC (I'm not sure, but I don't think it's actually gonna be wild. Depends on the definition...)  It will be steady and constant at its frequency. With exacting mathematics and construction, that frequency could be 60 Hz. But in my case it will probaly be a steady 45-90 or so Hz. Possibly I could get more power than this, as much as 12 Kw with enough torque at the shaft (or magnets in this case).
   More Rpm's would be great, but that aint gonna happen with my fine all wood and concrete construction - besides, it's most efficient at about 40 Rpm's.
   If it works I'll celebrate the occasion with a digital camera so I can post pictures of the whole thing. If it works well enough to actually do more than light up a bulb or two (which wouldnt be worth the cost or trouble of construction) I'll take it apart and film the process of putting it back together again, or of making another one. I'll also lay all the parts out on a piece of grid paper and take a picture so that people will know what sizes I used. (I often wonder why others don't do this...) None of that should really matter though, because what I am building isn't exactly new material, it's just another magneto stuck to a waterwheel. Sort of...

   I guess my newest, and last, concern is where to buy magnets and coil wire online, and what type of magnets to get, and whats a good price to pay for em, and do they ever wear out (under any circumstances?), and I guess that'll be it. Oh yeah, how much waste heat do you think this will generate? Probly depends on wire size huh...