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Forum Index : Windmills : Axial flux setup
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ProTow Newbie  Joined: 03/09/2010 Location: United StatesPosts: 29 |
Hello all.. You all have been a great help to This Newbie. I have learned ALOT so today im going to place my order for my mags. I want to use 2" round x 1/2" but after looking at the price and seeing the difference in price to the Rectangle 2x1x1/2" For my First gen im going to save a few bucks and get cheaper of the 2 for now. then after that ill go for the best of the best as the wife will let me LOL... so i draw up a pdf file so that you all can look at it and see if the size and placement is right. the disks right now are on 9" rounds but not sure if i have to go bigger or smaller. and this is for a 4 on 4 wheel hub for what i seen thats what alot of people are using so thats what i based this off of.. thanks again or should i just go with the 1/4" thick wedge shape mags? some say they are better than the 2x1x1/2 's James 2010-09-09_050530_windgen_mags.pdf If it works the First time You did something Wrong. |
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Perry Senior Member  Joined: 19/11/2009 Location: Posts: 190 |
Hey James, My ax-fx uses the rectangular magnets. I am curious, the 10 footer design is standard fare and well documented on the internet. This may seem like a strange question, but why the need to stray from the design. Many, many design tweaks on this oldie but goody machine have been made on other peoples dimes. I built mine pretty much from the book (with a few strengthening mods) and it has served me well. My next turbine will be more free-form, but not my first. Perry |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
Hi Perry.. Oh i dont know i just see what people say what is better and what not... I like the Try and True way. So im thinking im going to go somewhat by the book on this build until i get the hang of things. Im thinking along them same lines Stick with what works LOL... so i was looking on the net today and came across a excel file that helps out on this. it seems like it will work but Im lost on some of it. my main thing is how much wire am i going to need to make a 9 coil system. with 15agw wire for a 12 volt system this excel file will give me a ruff est. but i dont know all the details on it. thanks again Perry James If it works the First time You did something Wrong. |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
this is a PMA calculator i found on the net today. its a .xsl format. I dont understand all the settings it ask for but it might help others. Or hell it might even be on here and if it is Sorry for re posting it. James 2010-09-09_073650_PMA_calculator.zip If it works the First time You did something Wrong. |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ProTow As for using round or rectangle magnets, I've used round and had some problems. A round magnet makes "cancellation" a real risk and you have to size the coils very closely or it creates problems. I'd stick with the rectangle-shaped ones if it were me. I haven't looked at your pdf file yet, but the general rule is make the hole in the coil about the same size and shape as the magnets. Space the coils a distance equal to about half the width of your magnets. The ideal magnet placement shows a ratio of 4:3 -- magnet : coil using 12 magnet pair and 9 coils. This gives the near-perfect geometry so as one leg is falling in voltage another leg on the same circuit is coming up and so on, making it generate as much as is physically possible each rotation. Here's a .gif file that will demonstrate that harmony. As for how much wire to buy, get any size wire to make a "test coil". Once the magnets are placed on each wheel and the infrastructure is such that you can spin the thing at a known rpm, do that with a coil of say 30-gauge enameled copper wire with 200 turns. This will give you a very accurate "turns per volt" number. Jot that number down and then when it comes time to make the actual "operating" coils, you'll know how many turns for each coil and it won't be guesswork. The wiring configuration becomes an issue when it's all said and done as well. If you're going to charge a 12-volt storage battery and are doing a "traditional axial-flux design" then you'll wire three coils in series, with each coil 120* apart. Do this three times and then take one wire to common with the other three to each of three phases. Doing it this way, shoot for approximately 1.8 vac on your test coil. Any less won't make cutin and any more will serve only to warm the stator. This method by the way is called "star" and there's another method called "delta", which will up your amperage if you need to. That should be enough to chew on for a while. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
lol thanks Mac. so i should buy the mags and the disk first then buy the wire If it works the First time You did something Wrong. |
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niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
hi Protow i,m not sure about this but looking at your diagram there seems very little headroom to fit a conventional mounted (if thats what your thinking) stator ...if it is a conventional axial the hole in the center off the stator needs to have some clearance away from the the mounting studs which hold the alt/mill rotors together .....space to fit a stator (..with standard hand wound coils if you like.. ) does (.i think.) seem to run out pretty fast with smaller rotors like was mentioned before there are good published (cheap) books and other peoples builds online on axials that take into account some of the hidden factors ps...about the published books ...i admit to never actually buying one ...  ..it was only when someone actually put one in my face and told me go away and read it that i tried to appreciate the amount of knowledge that went into it... they are a good read ....like you i want to learn about these builds as wellniall |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ProTow I took a look at your PDF and it resembles the turbine shown in this Link. It looks okay so far from what I can see. As for the order in which to start, I'd start with the magnet-flux-return plates. They have to be thick enough to divert all the flux from 12 magnets back and forth without losing any. To test if you've got a thick enough piece, see if a paper clip will stick to the back side once all 12 magnets are in place; it shouldn't. If it does, the plate is not thick enough for your magnet choice. You'll need two plates, each with 12 magnets distributed in the order given in your PDF. The inter-magnet spacing seems a little close near the inside edge, but as long as you are able to fit your 9 coils into the mix with the proper inter-coil spacing over the large end of the magnets, the fact that the tops of the coils are a bit crowded together shouldn't matter much. The relative speed (feet or meters per second) is slower there and the amount of electricity produced is far less than where the magnet-to-coil speed is higher. I wouldn't worry about it. Remember that the stator will be "suspended" from brackets so it is positioned between the two magnet wheels. The wheels rotate while the stator stands still -- BUT the alignment of the stator against both magnet wheels must be held to tight tolerance. There needs to be a very small air gap, but not so small it allows physical contact between the whirring magnets and the stator or it will self-destroy in a jiffy. So, get the plates, then the magnets, then some acetone, then some CA glue then some enameled wire. Once you've got two plates of magnets spinning around a center core (hole), get back to us and we'll proceed. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
mmm....i,m not so sure Mac should the mounting studs not look a bit more like this in relation to the stator ? 
it would mean going up to a bigger rotor ... niall |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
niall1 Kinda depends on "which" studs you're talking about. The ones in the picture you posted are holding the magnet-holding plates. The ones I mentioned are stationary, hooked to the mount and wrap around from the outside, holding the stator in place. Maybe I missed something in his PDF. I'll go back and take a look, then come here with an edit if it's needed. Edit: Yup, I missed it the first go-round (tired eyes!). The very faint little holes in his picture are in the wrong place. You're right, they should be more to the center of the contraption or the donut hole in the stator will mean the stator will have to be ginormous! Wasn't going to let the cat out of the bag just yet, but I'm working on a "really easy" axial-flux build that will put this whole thing within the reach of just about anybody (I think). When it's done, I'll post the whole build. Remember, I build small stuff, so this will be an ax-fx with only about 7" diameter magnet wheels. I'll make it 3-phase and it'll likely top out at around 100 - 300 watts. Of course, if someone wants to fit it with a larger-diameter prop, it'll make more. I intend using only a drill press and maybe a welder (maybe not). All the hard parts will be "off-the-shelf" stuff available anywhere. For example, the "trailer axle and hub" assembly will cost about $4 US. Like I said, "really easy". . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
UGH more reading LOL... wooohooo I learn alot just in 2 post LOL about the 4:3 ratio . and yes Mac that link to the DIY site is where i first went to to try and learn about this.. And in Hugghs book it is setup the same way. But now thinking about it the 24 or 12 mag setup is for a Big Gen. im going for about 500 watts for the first one so im thinking to cut down on the mags and less coils will bring the cost way down. Just for my first one. ill redraw it at work and you tell me thanks agian.. James If it works the First time You did something Wrong. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ProTow Before we get too into this, what is the average wind speed where you are? We need to know that in order to size the prop and work this thing backwards, if we want it to actually work. The alternator size and magnet size can be tweaked here and there, but if the wind's not there, it still won't do diddly. What's your average wind speed? . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
Hey Mac well i want to say 5-7 MPH i know i get that daily. some days Like in winter it gets up higher and the summer a little lower. I need to get a thing to test the wind speed via the computer.. Ill make one one day the prop i think we talk about 6' dia.. If it works the First time You did something Wrong. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ProTow Okay, here's a little touch of reality: Drat! It's the wrong file type! I was trying to post a "screen shot" of Alton's Blade Calculator using 6-foot diameter as the blade size. I converted it to meters, by the way and left the TSR @ 7 along with everything else at their default settings. Anyway, with that size prop and a wind speed from about 5 to 10 miles per hour, the best you can hope for is about 41 watts optimum. Still wanna build this? . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
LMFAO damn it Jim.. ok lets start over to a point.. what size do you think the blades need to be for 5- 10 MPH winds for about 500 watts? then ill budget for the mags ect. I have seem anywhere for 12 to 24 mags total . see if that helps LOL If it works the First time You did something Wrong. |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
well after Reading the non metric and updated version of Hugh's book It all makes more sence. I was way off on alot of things. so back to the drawing board i go. sticking to the true and tryed way. ill make a new design up at work (meaning so i know what im doing ) so you can take a look at it... Damn this newer version is WAY easyer. Damn i love Google search LOL James If it works the First time You did something Wrong. |
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| arklan Newbie Joined: 18/08/2010 Location: AustraliaPosts: 29 |
dont use 15 guage wire wire, use 2 strands of 18 guage if u want that kind of thickness. 15 guage is thicker than u think and is quite hard to turn (personal experience) so youll be battling to get a tight solid coil. because it wont be tight the coil will end up being wider than youd like it to be and taking up extra room. |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
Good to Know that Thanks If it works the First time You did something Wrong. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I would say wire size 14 would be better but its a matter of what you can get your paws on. It all comes down to filling the area permitted with as much copper as you can while maintaining the right number of turns. If that means 1 strand or 6 strands it don't really matter as long as they are all wound together and it fills the area for the turn count needed. A loose wound coil is prone to failure, unless its totally impregnated with resin the copper strands will vibrate with the magnets passing and eventually wear through the enamel coating and short the turns. Just winding a coil and casting it in resin is not good enough, as the resin will not soak into the coil and will trap air in the windings and allow the copper to move internally. You only have to look at the amount of stator failures with burnouts and from pictures posted it is always one coil that takes the phase out. Why is it one coil or one phase? because of a construction problem. Any other reason it would take out the whole 3 phases not just 1 or a single coil. Ensure ALL coils are placed in the stator with the coil windings ALL going the same way. If you flip a coil over it will cause problems. If it takes you a week to wind the coils so be it, just get them right as they do all the work. Pete. Sometimes it just works |
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| ProTow Newbie Joined: 03/09/2010 Location: United StatesPosts: 29 |
Thanks Pete. that also Helps alot. do it Right the First time LOL If it works the First time You did something Wrong. |
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