5hp induction motor conversion advice

[makenzie71]

yeah to start with I carved a set of blades to replace the stop-sign blades.  She doesn't start up in near as low a wind, but she maintains in lower wind and she spins a bit faster.  It's not unusual for me to see her put out 6v in 10~15 winds.

http://www.photoartclub.net/turbine/turbine2.mpg

Next I have this 5hp motor I want to turn into a generator.  I've read the stuff by Zubbly...am still reading a bunch, actually...but there's a few questions I have that I wouldn't conjure up with his postings and project writings.  First how do I tell how many poles I have?

That's the stator and housing.  It was subject to a small fire...which obviously put some smoke in the unit but was otherwise unhurt...the yard claimed it as the controllers and everything were destroyed and a new setup came with a new motor.

I don't care what it produces as long as it's suitable for battery charging between 100 and 200rpm...hell, lower would be even better.  It's going to have a 10ft prop on it.  I understand that it'll only produce A/C electricity and that I'll have to rectify it to D/C and use a regulator to keep it at 14v or 24v...whichever is better (I'm learning that people think 24v and 48v are better but I've yet to stumble across why).

This is the rotor.  I'm wanting to use these magnets on it as these are similar to what Zubbly used on his 5hp motor, only thinner (what's the difference?):

http://cgi.ebay.com/20-Neodymium-Magnets-3-4-x-1-16-inch-Disc-N48_W0QQitemZ160028061915QQihZ006QQcat



egoryZ53142QQrdZ1QQcmdZViewItem

What would be the difference if I used even smaller magnets for a larger surface area?

I'd like to be able to whip something up without having to alter the coils, but I know that's likely not a possabillity.  If that's not a possabillity could I simply isolate the coils and wire it in a star configuration?

[Countryboy]

First how do I tell how many poles I have?

Look at the data plate on the motor.  A 2 pole will be about 3600 RPM, a 4 pole 1,750, a 6 pole 1,200, and 8 pole 900.

It's going to have a 10ft prop on it.

What did you use to determine prop size?  You won't get full potential out of this motor with only a 10 foot prop.  However, if you run a small 10 foot prop, and don't use as many magnets, you will end up with a very heavy duty 10 footer.

I understand that it'll only produce A/C electricity and that I'll have to rectify it to D/C and use a regulator to keep it at 14v or 24v.

Regulator?  The batteries will self-regulate the voltage.

whichever is better (I'm learning that people think 24v and 48v are better but I've yet to stumble across why).

Smaller wires can carry higher voltages.  By using a higher voltage, you can get away with using smaller (cheaper) wires.

I'm wanting to use these magnets on it as these are similar to what Zubbly used on his 5hp motor, only thinner (what's the difference?)

What would be the difference if I used even smaller magnets for a larger surface area?

Smaller or thinner magnets mean you will have less potential output.  Stop caring about magnet size - it's irrelevant.  You should be caring about total magnet volume - that's what's important.

Zubbly's rule of thumb is 140-150 watts potential output per cubic inch of magnet material.

[makenzie71]

Look at the data plate on the motor.  A 2 pole will be about 3600 RPM, a 4 pole 1,750, a 6 pole 1,200, and 8 pole 900.

It's 1175.  That would make it a 6 pole stator, right?  Which would mean there should be 6 sepearate coils, correct?

What did you use to determine prop size?  You won't get full potential out of this motor with only a 10 foot prop.  However, if you run a small 10 foot prop, and don't use as many magnets, you will end up with a very heavy duty 10 footer.

I didn't...I made the 10 footer for something else and thought I could use it here.  What's a good way to determine proper size?

And how could I run this motor without magnets?  If I understand it correctly the only way to run it without magnets would be to run it at slightly higher RPM than rated + use running capacitors.  There's no way I could get it to spin nearly 1200rpm.  If I'm missing something I'd love to know what it is (<- that's an actual request, not smartass remark).

Regulator?  The batteries will self-regulate the voltage.

Will the rectifier automatically bring the A/C input to battery charging voltage?  I'm still learning how they determine output with them and how it's effected with the fluctuations of wind input.

Smaller wires can carry higher voltages.  By using a higher voltage, you can get away with using smaller (cheaper) wires.

Thanks for clearing that up for me.  I'll be doing some research on it to learn more but thanks for pointing me in that direction.

Smaller or thinner magnets mean you will have less potential output.  Stop caring about magnet size - it's irrelevant.  You should be caring about total magnet volume - that's what's important.

Zubbly's rule of thumb is 140-150 watts potential output per cubic inch of magnet material.

Awesome.  So then using smaller magnets would be better if I understand correctly...they're cheaper and you can easily fit a larger valume in the same space.  Probably only better way would be machining groves into the rotor and solid magnets.

How many magnet banks sould I fit on the rotor?  Zubbly's setup has 3 rows of 15...should I stick with the three rows if I've got 6 poles?  I'm not sure how to figure that.

Thanks Countryboy!

[SparWeb]

Makenzie,

I'm in the middle of converting a 3HP motor, so I'll share with you what I've done so far.  I'm not the only one, either.  These postings are most often found on the "Mechanical" subsection.

First, the stator:  You have 9 wires coming out.  You already have enough wires to enable a HI/LO voltage switch, which IMHO is an advantage of these conversions.  For more info, you could do net searches on "star-delta connections", or "wye-delta connections" on 3-phase motors.  If you want to go the extra mile, you need to find is the "star point" and cut it.  Solder on 3 more wires, and with all 12 coming out, you will have available about 8 different wiring combinations, should you desire.  

Second, the casing:  this is where there should be a data plate.  It is most likely (but not guaranteed) that you have a 4-pole motor, and the speed on the data plate will be a dead give-away.  If it is a 4-pole, the speed will be between 1500 and 1800 RPM (depending on whether you live in North America or not).  If the speed is closer to 3200-3600 RPM, then it's a 2-pole, if more like 700-800, you have stumbled upon an 8-pole motor.

Thirdly, the rotor:  The fundamental step in converting a 3-phase motor to being an alternator is to apply permanent magnets to its rotor.  My approach has been to build a rotor from scratch.  It's been somewhat time-consuming, but not very technically difficult, if you know a bit about machining metals, and it helps that I can sneak into the machine shop at work after-hours.

Keep your eye on the board, I'll be posting a diary of my work one of these days...

PS: I picked magnets with holes in them, so that I can screw them down directly.  I love glue, but I don't trust it in tension.

[Countryboy]

It's 1175.  That would make it a 6 pole stator, right?  Which would mean there should be 6 sepearate coils, correct?

Yes, it is a 6 pole, but no it does not have 6 separate coils.  You will have far more than 6 coils.

I didn't...I made the 10 footer for something else and thought I could use it here.  What's a good way to determine proper size?

Decide how much power you want.  Then, look at the power in the wind to determine prop diameter.  Then, build a genny that can harvest that windpower.

Or, build a genny to produce a certain amount of power, and then look at the available power in the wind to determine what size prop you need to maximize the potential of the genny.

And how could I run this motor without magnets?  If I understand it correctly the only way to run it without magnets would be to run it at slightly higher RPM than rated + use running capacitors.  There's no way I could get it to spin nearly 1200rpm.  If I'm missing something I'd love to know what it is (<- that's an actual request, not smartass remark).

I believe you can overspin a motor by 10 or 15% of rated speed to produce power.  It's not as efficient as using magnets, but it will work.

You can also gear up the genny from the blade rpm.  Again, massive inefficiencies, but it will work.

Will the rectifier automatically bring the A/C input to battery charging voltage?  I'm still learning how they determine output with them and how it's effected with the fluctuations of wind input.

The rectifier ONLY changes AC current to DC.  The batteries will hold the voltage down.  Once the genny reaches cut-in voltage, the batteries hold the voltage there.  After that, the power fluctuations are amperage changes.

So then using smaller magnets would be better if I understand correctly...they're cheaper and you can easily fit a larger valume in the same space.  Probably only better way would be machining groves into the rotor and solid magnets.

You understand incorrectly.  'Small' magnets has NOTHING to do with volume.  Volume is volume.  Whether you calculate the sum total volume of many small magnets, or the sum total of fewer larger magnets, volume is still volume.

How many magnet banks sould I fit on the rotor?  Zubbly's setup has 3 rows of 15...should I stick with the three rows if I've got 6 poles?  I'm not sure how to figure that.

IIRC, the 3 rows of magnets on Zubbly's conversion were 1 pole, of the several total poles on his rotor.

You will need to decide how thick of magnets you will be using.  Then, calculate what your rotor diameter will be that you add magnets to.  Divide into 6 equal sections so you can put 6 poles on the rotor.  Calculate the skew.  Measure how much space you have left in the section, and see how many magnets will fit in that space.

[makenzie71]

Decide how much power you want.  Then, look at the power in the wind to determine prop diameter.  Then, build a genny that can harvest that windpower.

Is there a calculator somewhere to tell me this?  All I know is that my particular locations sees average yearly wind speeds of 8.3mph at ground level and 13.8 at 15 meters.

You understand incorrectly.  'Small' magnets has NOTHING to do with volume.  Volume is volume.  Whether you calculate the sum total volume of many small magnets, or the sum total of fewer larger magnets, volume is still volume.

no I understand...smaller magnets will fill more volume...given the area I have to work with I'll be able to use a larger volume with smaller magnets than with larger ones.  Take a 2" cube, for example:  that's a total of 8 cubic inches.  Put a 2 inch sphere in that cube and you'll be left with roughly 3.8 cubic inches of unused volume.  Put 32 .5" diamter spheres in there and you'll only have roughly 2 cubic inches of unused space.  So I can use smaller magnets and save money in the long run, but have a larger volume...if total magnet volume is what matters.

Approaching from a slightly different angle...would it be possible for me to remove the coils from inside the stator and insert seperate, new coils and run it like the drum brake alternators (but inverted, obviously)?  It seems to me that it would be easier to approach that way as I have a decent understanding of how that variety of alternator works.

Thanks again, coutnryboy.

[makenzie71]

nevermind about seperating the coils...I'll just figure out how to tear what's in there apart and figure out how it's all wired.  It's just daunting to look at in it's factory state of being.

I would like to know, though, why the magnet banks are skewed on all the conversions I see?  What happens if straight bars are used?

[makenzie71]

Also, is there a way to increase the number of poles?  Everything I see seems to indicate that the higher the number of poles, the lower to start up rpm.

[Countryboy]

Is there a calculator somewhere to tell me this?  All I know is that my particular locations sees average yearly wind speeds of 8.3mph at ground level and 13.8 at 15 meters.

Is there a calculator to tell you how much power you want, or a chart which shows how much power is in the wind?  You have to decide how much power you want.  Do a google search of the board for available power in the wind.

no I understand...smaller magnets will fill more volume...given the area I have to work with I'll be able to use a larger volume with smaller magnets than with larger ones.

No, you DON'T understand.  Volume is volume is volume.  We are talking about total volume of magnet material.  Calculate how much volume each individual magnet contains, and then multply by the number of magnets to obtain the total volume of magnet material.  For a given space, the sum of many small magnets will not exceed to sum of one large magnet.

Take a 2" cube, for example:  that's a total of 8 cubic inches.  Put a 2 inch sphere in that cube and you'll be left with roughly 3.8 cubic inches of unused volume.  Put 32 .5" diamter spheres in there and you'll only have roughly 2 cubic inches of unused space.  

Grr.  We aren't using spherical magnets, are we?  And if you want to cram the maximum amount of magnet volume into any given space, you would use a magnet the exact dimension of that space.  A 2 inch cube magnet still has more total magnet volume than your spheres.

Figure out what maximum watts you want to obtain.  Divide that by 140 to find out how many cubic inches of magnet material you will need.  Then, figure out how to fit that magnet volume onto your rotor.  

Approaching from a slightly different angle...would it be possible for me to remove the coils from inside the stator and insert seperate, new coils and run it like the drum brake alternators (but inverted, obviously)?  It seems to me that it would be easier to approach that way as I have a decent understanding of how that variety of alternator works.

The brake drum alternators are axial flux generators.  Motor conversions are radial flux.  You can rewind the motor, but it will still be a radial flux genny.

Please do yourself a really big favor by spending a month or two reading this site and otherpower.

[dinges]

http://www.otherpower.com/images/scimages/4/zubbly2.pdf

http://www.otherpower.com/images/scimages/4/z_conversion_all.pdf

[makenzie71]

We aren't using spherical magnets, are we?

It doesn't matter what shape they are, though, and do the math with any other shape magnet you'd like and it'll be the same...if the propper size isn't available, more smaller magnets will yield a higher volume in the same cavity.

I am reading and researching and I'm constantly finding new things to ask questions about, and I have been trying to find wind power information for my general area but am only finding annual average speeds (forgive if there's a conversion between the two I'm unaware of).  I do appreciate the matters you have helped me on, though.

[dinges]

The fact that you asked about why to skew the magnets suggests you've done VERY little reading on the subject of motor conversions.

Do what Countryboy suggested: read. IMHO, he already has been very patient with you.

Read everything by Zubbly; stories, diary, posts, IRC gallery photos, in short, everything.

http://www.fieldlines.com/user/zubbly/stories

http://www.fieldlines.com/user/zubbly/diary

http://www.anotherpower.com/gallery/zubbly

http://www.otherpower.com/images/scimages/4/zubbly2.pdf

http://www.otherpower.com/images/scimages/4/z_conversion_all.pdf

When you've read that, do a google search on this board for 'motor conversion'. You'll see much more users who have or are converting induction gennies. Read that too.

If you do all this, 95% of your questions on the subject of conversions will be answered. Then, come back with the remaining 5%.

BTW, if you expect to become an expert on the subject of calculating wind, power requirements, prop size, motor conversions, etc. you'll be in for a surprise. I've been on this board for more than 2 years. Have built 2 axial flux gennies. Have and am converting a few motors. And I consider myself an utter beginner.

[wildbill hickup]

makenzie71,

I agree with Countryboy and Dinges. First don't do anything to the motor, or buy magnets YET. When I started I like many of us here chomping at the bit to get started only read enough to be dangerous and completely distroyed a stator winding only to find out that there was a much easier way I also bought some magnets that I wish I'd never bought. It will take you at least a month to read, research, and digest the writings of the conversion master we refer to as Zubbly. In addition to those things allready mentioned Diaries, photos, stories and the like also do a board search for Zubbly and read the many questions (mine included) that Zub has been asked in the past and he has answered to many people. It WILL take some time, and I know you want to get going, but be patient it will pay off. In addition to that Ed at windstuffnow has an excellent program on wind power and rotor size that you can download for only $5.00, probably the best 5 bucks you ever spend. That's a big honkin motor that you have there, capable of some pretty good power, it would be a shame to ruin it. Zub's series 1,2,3 on induction conversions and his other stories will answer the questions you have like, skewing magnets, and why, separating the leads for the windings, and why, magnet size, rewinding stator (not for the beginner IMHO), poles, rectifiers, and much more. Other searches will teach you how batteries will regulate genny output. So again IMHO set the motor where you can look at it (for inspiration) BUT don't touch it until you have read much more. In your title you ask for advice, this is mine.

Wildbill

[wildbill hickup]

By the way, nice little genny you have there, suggest doing a lot of expreimenting with blade design on it before you get around to cutting 'the big ones' all that you learn from that will apply to your bigger mill, little blades cost less to make, and are far less deadly or damaging than big ones if they come apart. Another thing I forgot to mention as far as my experience goes. With a big mill 5hp you also must concider very carfully how you are going to get it in the air. For me anyway this has been much more of a challange than building the mill itself. The windload on these bigger mills is quite large. This will be a mill that you not going to just stick up on a chunk of pipe. Many here have put much more time, effort, and money (and in Zubbly's case blood and bones) into their tower than the mill itself. I am not trying to be a wise-#$$ hear,or discourage you and I'm being honest my 3 hp Baldor conversion is still sitting in the barn because I DIDN'T concider these things and now I'm haveing difficulty finding a suitable place to put, it, and pay for it, and the concrete foundation, and the guy wires, and their anchors, etc,etc. Ed's program will also help caculate wind load (rotor thrust) too so it will be very helpful. DanB's postings are very helpful on tower design, raising, materials, what not to do etc. Best of luck!!!!!

Wildbill

[ghurd]

I'll go a step more and say after reading everything you can find, build a small one first. Or 2 or 3.

They don't have to be great to show some of the problems you will find.

Much of the information floating around shows 'how not to make a bad one', more than 'how to make a great one'. If you know what I mean. For the first one, try to make something not bad.

Stuff I learned...

Thicker magnets help. Those 1/16" thick magnets are too thin. 3/16" is about the minimum even for something small, and thats marginal without fairly tight tolerances.

I understand your thinking with smaller dia magnets, but its a bugger placing lots of them without a Zubbly style cage.

G-

[powerbuoy]

It would also be good to get another picture taken from the stator head (slightly different angle). So that one can have a better look at the coils. Just want to make sure that you are not dealing with a rewound motor ... somehow the coils seem to be to large for a six pole machine, but we'll need a better shot to see that clearly.

Powerbuoy

[Gary D]

Some of the people here on the board have a site to help out. There is a calculator there to give you an idea of available extractable power at different windspeeds and blade diameters. All you need to do is punch in the numbers, perhaps this will help a bit, after your researching, that is(if my link works)... Gary D.

http://www.reresource.org/formulas/windpower_calculator/

[makenzie71]

To point out I have all of the bits about Zubbly's conversions printed out and I'm studying them...and I learned why the magnets are skewed.  Saying that it prevents cogging seems a lot simpler than the response I got to that question.  It's a discussion forum...if you don't like what you're reading then stop and go check out someone else.

Wildbill...the tower is simple in my case.  Having a 125ft boom makes erecting a tower a simple task.  I also have several fifty and eighty foot towers...these all had 200~400lb radios on them and werent stressed so I'm pretty sure they'll hold up my generators.  If I can make the 5hp motor produce half it's potential (1500w) it'll be stock at the top of a 60ft radio tower.  I also don't consider my blades a prioraty...as I've said before, this is all experiemntation mostly to kill time and to learn how all this stuff works. When it comes to actually generating reliable power I'll be buying composite blades and generators ready to run.  I've had a good test of my structural quality, though lol...had to dodge a critter on my way home from work last night and chucked my 11ft prop out of the truck (should have taken it apart before heading out).  Skidded down the road at 70mph and dug into the ditch.  I saw it cart-wheeling a bit which hurt after carving the things with a knife and sandpaper.  Broke about 6 inches off one blade when it dug into the ditch and it bent my hub all to hell but I have more of those.

these are full size pics of the stator...all I can say about it is this is how it came from the factory.  They'd only buy new motors for this stuff.

http://www.photoartclub.net/turbine/stator2.jpg

http://www.photoartclub.net/turbine/stator3.jpg

Again, I appreciate the help!

[makenzie71]

also for anyone who thinks I'm just jumping all over this 5hp motor, the motor I'm actually working on currently is a .5hp blower motor.  The big 5hp one is a "plan" at the moment...that's about it.

[zubbly]

hi makenzie71,

your motor in the pic is definately a 4 pole unit. it has 36 stator slots and is wound one coil per slot, coil spans of 8-10-12. with the nine leads it is also likely 230/460 volt.

that winding is very usable as it is. do your rotor first and get some bench numbers on output. if it seems like adding the 3 additional leads to it would help meet your required cut in speed, it can. always be done later.

each conversion is a little different than even ones of a comparable size. your mag pole width should be the same as the span between the 1-8 coil span. the length of the mag pole should be as close to equal as the length of the lamination set.

you will likely find that 3/4 round by 3/8 thick mags should work out good for it. if it turns out that 3/4 wide mags makes the pole too wide or too narrow, 1/2 wide by 3/8 thick will make it easier to get the ideal mag pole width.  you may also find that the #29 skewed mags will work out also.

good luck with the project and hope all goes well for you,

zubbly

[makenzie71]

Thanks Zubbly!

Can you clarify how I'm supposed to know how many poles the motor has?  All I see are references to rpm but I'm sure I'm looking in the wrong place.  I already started machining the .5hp rotor down under the assumption that it was a 6-pole motor (specs same as the 5hp motor, only 110v) but I'm concerning that might be incorrect.

With this one I was planning on using either the .75X.375 magnets but I would like to use "longer" ones if possible.  Should I have a problem using .75X.5?  An acquaintance of mine has about 100 of them and I had some car parts he wanted...so they're what I have available.

Any idea what I can expect to see in the way of output from the factory coils?

[stephent]

Might want to look at this set of coils again. (4 o'clock position)

http://www.photoartclub.net/turbine/stator2.jpg

What I see in that pic magnified a bit--looks a bit cooked in one area of a coil.

Were you planning on using the original coils?

Doesn't look like just smoke damage to me, the winding holding threads have been cooked/burnt back a bit, with a "flashover" right close to the laminates.

Might find a friendly electrician with access to a "megger" and stick a test at 500 volts across that coil and ground.

[zubbly]

hello again,

basically, unless you know just what you are looking at in the winding, your name plate says it all.

what you have:  36 stator slots

                18 coils (1 coil side per slot)

                coil span, 8-10-12

                6 groups of 3 coils

                6 groups divided by 3 phases = 2 coil groups per phase

                connection= consequent pole (consequent pole = 2 poles produced per    

                coil group)

                your winding is a typical 4 pole consequent pole machine    

3/4 by 1/2 inch mags will work fine. just be sure they will all fit on the rotor face and that you will be able to form the proper size mag pole with them.

turning your rotor down the required amount to accomodate the 1/2 inch thick mags may take the rotor surface under the aluminum bars that are pressure cast into the rotor. if you get under them, your rotor lams fall apart.

do your calculations and diagrams on paper to make sure all will fit and work before machining rotor.

zubbly                                                      

[Countryboy]

Zubbly,

  Earlier he said the name plate said it was 1175 RPM.  That should make it a 6 pole, shouldn't it?

[makenzie71]

the black is just soot...being a retard I used B12 chemtool and a lighter to flame a bunch of flies that were buzzng around and one of the little bastards flew right into the stator...which I had just been spraying out with the same cleaner.  I had a little CO2 tank right there, though, and purged it almost as soon as cleaner flamed up and killed it.  The ties melted but that's it.

If for some reason it's screwed up we've got a 25hp motor I'd love to tinker with...

[Phssthpok]

 Zubbly's rule of thumb is 140-150 watts potential output per cubic inch of magnet material.

Lemme see if got this right:

The magnets in my toasted windgenny are 1-7/8" x 2-1/16" x 5/16"

Converted to decimals, thats: 1.875 x 2.0625 x .3125 = 1.20849blahblahblah...

Call it 1.21 cubic inches.

This genny has (had) 8 of these magnets. 8 x 1.21 = 9.68 (call it 9.65 since I rounded up earlier)

9.65 CI total magnet volume x 140 watts/CI = 1351 watts peak potential.

You're saying this little genny (assuming less than maximium potential achieved) peaks out at just over 1KW!!? Or does this rating only hold true for NdFeB magnets?

Is my math off?

[RP]

Yeah, Zubbly's rule of thumb is for Neos

[wildbill hickup]

125' boom, several 50 - 80' towers.......... now your making me druel :-> After building a few of these conversions or a couple of axle flux machines (like DanB's) you may find that some of the 'store bought' one's are pretty pale in comparison. Sorry to hear about the blade and hub. Carved with a KNIFE and sand paper now that's bringing a new meaning to the word 'whittle' I can just picture a guy sittin on the front porch in an old strait-back rocking chair two small tree trunks 10 or 12' long nearby, a pile of wood shavings all around him and a half carved blade accross his lap, good ol' 3" Uncle Henry pen knife in hand caption above 'Yep just passin' time'. Wish I could draw. What a cartune to post on the board. Anyway sounds like your starting to get hooked. Be careful this stuff is known to be pretty addicting. Have fun!!!!

Wildbill

[makenzie71]

Yeah I don't have the wood workin' machinery or access to a shop that does wood work like some of you guys...and no one around here sells a drawknife.  So I had to make a drawknife and then that's the only thing I have to do any real carving.  It was real fun...and why my air foils suck.

I got to thinking about the conversions and store-bought units last night and the potential output of each.  As I don't have access to the machinery to make precise conversions I might see if anyone who "can" do the conversions precisely will work over my 5hp or 20hp motors in exchange for a tower.

...might offer to start making towers for folks here, anyway.

[zubbly]

hi countryboy,

yes, i think he did mention 1175 rpm.  1175 rpm is a 6pole machine.

the winding in the picture is definately 4 pole. i probably wound a few thousand of those in my time.

it is possible that his motor was originally 6 pole and it had been converted to a 4 pole. possibly the numbers on the name plate have been damaged and it looks like 1175. that part i can't see.  what i do see is a 4 pole winding.

zubbly

[wildbill hickup]

Even a good hand saw and a sharp chisel will speed the rough layout of the airfoil and angle of the face of the blade along. Many of the fancy machine shops we have on the board are just basic hand tools, grinders, skill saws, chain saws, chisels, files, and the such. Get it close and then get after it with your homade draw knife. Sometimes you can find some pretty good deals on draw knives on Ebay. I usually go for the old beatup, rusty ones they don't look pretty and can sell pretty cheap. Once you get it home clean it up with stealwool and WD-40 or mystery oil file a new edge, hone it fine with a good stone and presto. I try and find the really old hand forged ones, boy that steel takes a razor edge, while a little on the soft side (razor edge doesn't last long) just a couple of passes on the stone while your working (I keep one right beside me)does the trick.

As far as the conversions go, the only real machining is turning down the armature so the magnets will fit, depending on the magnets you use, maybe fabricating a 'cage' tho help you align them. I'm sure if you don't have a machine shop in your area someone on the board (in your area) will help you out with that. Zub used to build motors for folks, but I don't know if he still does. It's really not the hard except for the armature and calculating the amount you have to remove(formula on one of Zubs many postings).

By the way where are you? I'm in Vermont USA. If your close I'd be glad to turn the armature for you if you like. If you use the curved, skewed, rectangular magnets you won't have worry about building a cage.

As I mentioned before, that little mill you have can be a source of pages of information, measureing the actual wind speeds in your area, blade design, air foils etc, collecting the basic info from that can be very helpfull in the design of your bigger mill. Many of the folks here spend countless hours, days, weeks collecting data fron mills that could barely light a small lightbulb, but the info they get from these tiny models can then be scale up to help design bigger versions.

I can't even count the number of different types, sizes and shapes of blades I have for my little mill, some complete failures, some not so good, some good, but I didn't have to take as much time and money making them, the indiviual blade are only about 2 feet long instead of 5 or 6 or 8' that's a lot of carving, sawing, etc saved and the data from them can be scaled (to a reasonable exstent) to make larger ones

Just a few thought for you to knaw on.

Wildbill

[makenzie71]

The label definitely says 1175 rpm and there's no remanufactured mark or anything, and we shy away from buying anything used or remanufactured here.

Is RPM the only determining factor for poles?

...I'm not even going to pretend to know either way...

[makenzie71]

hey zubbly email me!  addy is in my user info