Author Topic: New Idea Makes Box Fan Conversion Very Easy  (Read 19275 times)

0 Members and 1 Guest are viewing this topic.

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
New Idea Makes Box Fan Conversion Very Easy
« on: July 04, 2005, 03:44:46 AM »
This project was started long ago and is finally finished.


The idea was to overcome some of the common problems when trying a small, cheap, and easy first windmill.  And have a good chance of having it actually work!


Box fans seemed like a good place to start. My neighbor threw this one away.

The main problems for box fans are magnetic cogging and high coil resistance.


My "big new idea" is using only 4 magnets for the 6 coils.  This almost totally eliminated the magnetic cogging common to 6 magnet armatures.


This also allows the coils to be seperated into 3 series pairs, and that reduces the coil resistance.


Tools required are very basic.  I only used a pencil, hack saw, file, small vice, wire cutters, pliars, screw driver, razor blade, 1 hour epoxy, soldering iron and solder, hot glue gun and hot glue. I do not believe that hot glue is the best choice to insulate and hold wires in place, but I did not think this would work as well as it does.


This motor is from a 20" box fan. The fan blade will surely turn it, but it will be fall before I can test it in the wind. Too many trees here.

The motor has bushings instead of bearings, and therefore will wear out sooner.

If there is a copper pin through the laminations, it should be removed.

This motor did not have one.

The name plate sticker reads 120V AC, 60HZ, 2.1A.


The magnets were placed on the end of the armature, marked a line with a pencil, cut with a hack saw, cleaned up with a file, then epoxied on the magnets N/S/N/S.


The stator had 4 wires in parallel wound from coil to coil in series.

These wires were cut allowing the wires from deep in the coils to be long.

The other end was carefully unwound from the outside of the coils so they were long enough to work with.


The insulation on all the ends was stripped about 1/8".

The meter set to ohms found ends of the same wire, so they could be reconnected properly.

Take care when soldering, so no solder drips onto the coils.

The soldering was time consuming and tiring. Don't expect to do it in an hour.


The sketch shows how I reconnected the wires of opposite coils. 1A to 1B. 2A to 2B. 3A to 3B.  The outputs are AC, and need rectified to DC for battery charging.

That is covered in depth elsewhere on this board.


The wires were insulated and held in place with hot glue. Like I said, probably not a good idea.


If one pair of coils has a very low output, one coils ends should be switched.

Meaning the wire going to the other coil now becomes the output, and the former output now goes to the other coil.


Each reconnected coil coil is 9 ohms, each pair in series is 18 ohms.


Each coil in this conversion makes 0.45 amps into a 12V battery at 650 RPMs, 1.2 amps at 800 RPMs, and 0.75A at 1100 RPMs.

With all 3 coils operating at 1100 RPMs, that is 2.25 amps for about 30 watts output.


One pair of coils was faulty. This has reduced the total output, but has nothing to do with the construction. (3A and 3B are the faulty coils) Maybe that is why it was in the garbage, but it probably happened from so much handling for so long.


These magnets are most probably over powered for this project. 3/4 x 3/4 x 5/16" N45 grade neos. They just happened to be here and fit nicely, so I used them.


The whole thing.





Nothing to exact.





Not very pretty.





The wiring connections for one pair of coils.

The top shows how it looks aon the laminations.

The bottom shows how it would look if they were all seperated.





I hope this helps someone looking for something small for a first try.


Any and all comments welcome.


Thanks to everyone who very patiently helped me with this unusual conversion!

G-

« Last Edit: July 04, 2005, 03:44:46 AM by (unknown) »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #1 on: July 03, 2005, 10:11:21 PM »
Missed the coil layout.





G-

« Last Edit: July 03, 2005, 10:11:21 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #2 on: July 03, 2005, 10:41:12 PM »
New user here*grin*


I just did one of those cheapo "lakewood" box fans too, but I rewound the laminates using 150 turns of #22 AWG wired in series and used 6-1"x1/8" Neos.....


On a breezy morning I couldn't get it to spin up by itself(cogs too much), but after giving it a spin by hand my multimeter showed it was producing 31.4 volts AC using the 20" fan blade.


Today I added a bridge rectifier (25 amps-50 volts) and spinning it by hand I can get a 12 volt bulb to light.


I really don't know what I'm doing yet so I might be heading off in the wrong direction, but right now I'm looking at the Zubwoofer stuff hoping I can build a rotor that will spin up by itself....

I'd really like to use this to keep a few 12 volt trolling motor batteries topped off at my deer hunting camp.

« Last Edit: July 03, 2005, 10:41:12 PM by ZooT »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #3 on: July 03, 2005, 11:30:45 PM »
Welcome aboard!


This was about the same fan, a Holmes brand.


Reducing the cogging was the 'New Idea'. That is the main problem with these.

With 4 magnets the cogging is almost totally gone.


And it sure was easier than a re-wind!


The fan blade from this motor is now turning a tiny little induction conversion.

This one turns just as easy, and the other one even has bearings!

(check my photo files for Ugly20 or WideOpenSpaces)


I believe a 'Teflon' carrying oil (like 'Slick-50', 'Greased Lightning' or 'T-Plus') will help the bushings spin much more free and last longer.

Just personal experience, but T-Plus is in all my cars because it saves far more than it costs in gas alone, and they run cooler.

No connection with any of them and me.


Keep an eye out for another donor fan to try this.


G-

« Last Edit: July 03, 2005, 11:30:45 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #4 on: July 04, 2005, 01:42:12 AM »
The output specs have a typo or 2.

Total output with the 2 working pairs of coils is 1.5 amps.

G-
« Last Edit: July 04, 2005, 01:42:12 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

hiker

  • Hero Member
  • *****
  • Posts: 1661
  • BIG DOG
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #5 on: July 04, 2005, 03:11:33 AM »
this little fan motor had the coils in the center--so i placed the mags on the inside case[14 hd mags]..this way you don"t have to worry about the mags flyin off..

motor had 14 coils--i rewired with #14 wire--i belive 1 had room for about 10 turns..

it puts out about 10 amps--somthing like 35 volts out..lights up two 50watt lights-- made it for my little 1916 engine[it powers the buzz box]makes the spark for the spark plug--any way it worked out great for that--no need to carry around a big auto battery anymore just to power the buzz box........later.

 

« Last Edit: July 04, 2005, 03:11:33 AM by hiker »
WILD in ALASKA

hiker

  • Hero Member
  • *****
  • Posts: 1661
  • BIG DOG
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #6 on: July 04, 2005, 03:14:19 AM »
thats a 2hp briggs and strat in the above picture--used it for testing the alt..
« Last Edit: July 04, 2005, 03:14:19 AM by hiker »
WILD in ALASKA

hiker

  • Hero Member
  • *****
  • Posts: 1661
  • BIG DOG
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #7 on: July 04, 2005, 03:26:20 AM »
here it is --mounted on the 1916 motor -with a temporary mount--its powering the buzz box and one 50watt light--bad picture-i had the light bulb right in the sunlight..

  well i hope i didnt steal your post--just thought i might show you how much power you can get from those old fan motors...i have a bigger fan motor layin around that has 33 coils--single phase--should be a fun conversion...

« Last Edit: July 04, 2005, 03:26:20 AM by hiker »
WILD in ALASKA

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #8 on: July 04, 2005, 08:31:01 AM »
Is that one of your ceiling fan motors?

G-

« Last Edit: July 04, 2005, 08:31:01 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

Norm

  • Hero Member
  • *****
  • Posts: 1841
  • Country: us
  • Ohio's sharpest corner
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #9 on: July 04, 2005, 09:36:48 AM »
 G,

  Nice goin', glad to see you're finally using

pics ...Just about the time you started using

pics...my digital went south, Oh...Well good excuse to get a new one.

  I could just use ceramic magnets for a

project like this?

  I know what might happen to a couple of

 old 20 inch box fans when summer is over!

                  ( :>) Norm.

                   
« Last Edit: July 04, 2005, 09:36:48 AM by Norm »

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #10 on: July 04, 2005, 10:00:28 AM »
Well....the reason why I rewound the motor was because it let the smoke out in the kitchen here*L*


Anyways does anyone have any ideas about or thoughts about how large of a rotor I'd need to get this thing to spin up by itself in 10 mile an hour gusts?


If I'm being vague or not giving the right info it's because I don't know much about this stuff yet

« Last Edit: July 04, 2005, 10:00:28 AM by ZooT »

Norm

  • Hero Member
  • *****
  • Posts: 1841
  • Country: us
  • Ohio's sharpest corner
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #11 on: July 04, 2005, 12:46:55 PM »
On a breezy morning I couldn't get it to spin up by itself(cogs too much), but after giving it a spin by hand my multimeter showed it was producing 31.4 volts AC using the 20" fan blade.


Today I added a bridge rectifier (25 amps-50 volts) and spinning it by hand I can get a 12 volt bulb to light.




  You don't really know what the rpm is ...do you?

Here is a quick simple way.....



  count the number of threads per inch ...grab the nut and see how far it travels in 10 seconds.

...if you're really a new guy you might have missed this.....


http://www2.suite224.net/~peppysue/


a three blade 3ft. diameter rotor with a wide root

might spin this thing okay....

                   ( :>) Norm.

« Last Edit: July 04, 2005, 12:46:55 PM by Norm »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #12 on: July 04, 2005, 09:46:29 PM »
Norm,

Maybe thick ceramics? I don't know.

These neos are serious magnets for what I expected.

I was kind of surprised at how low the VAC open was,

at 800RPMs it was 30VAC, 650RPM was 20VAC.

I expected more volts with all those turns.


It may have more potential in a 3-phase style wiring,

but with only 2 working, it will have to wait for the

next one.


Star / Wye or Delta? Not sure.

Had a feeling Delta would be better.


This is just a little too different for me to guess.


G-

« Last Edit: July 04, 2005, 09:46:29 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #13 on: July 04, 2005, 09:57:40 PM »
I just stick on fan blades of many sizes,

then PVC of many sizes,

and then make a guess!


I'm with Norm for the first guess,

something kind of wide at the root.


The 20" fan blades I have do pretty well

for torque compared to many others.


Been thinking about buying a new one,

rewind with microwave wire,

but all the rest the same,

with 4 magnets, and 3 coil pairs.


G-

« Last Edit: July 04, 2005, 09:57:40 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #14 on: July 05, 2005, 02:25:46 AM »
Norm,


I tried some 3/4"x1/4" round ceramic magnets before I got the neos and it didn't produce but 3.4 volts AC at about 800 RPM's on a lathe.

Thinking the ceramics just weren't strong enough to saturate the coils considering that the coils are over a half an inch thick.

« Last Edit: July 05, 2005, 02:25:46 AM by ZooT »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #15 on: July 05, 2005, 08:18:10 AM »
Hey ZooT,

A few things.


About not turning in the wind, but lighting a bulb.

A bulb acts about like a short, and will make it much start MUCH harder with these small blades.  Some of my experiments would speed stall in a light wind, but not even turn connected to a bulb in the same wind.


Will it start with no load and all that cogging?

I don't figure it will, that's why 4 mags and 6 coils seemed like a very good idea.

Even better when it worked!  ;)


How many ohms did 150 turns of #22 come out to?


That was 150 turns total, 25 turns per lamination tooth, right?

Not 150 turns per coil?


You have me wondering if I should rewind this with heavier wire so all 3 phases work.

There is just so little information about the small stuff.


G-

« Last Edit: July 05, 2005, 08:18:10 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #16 on: July 05, 2005, 08:31:11 AM »
With what Hiker is getting from hard drive magnets, maybe try a fan with some of those? 2 or 3 thick I bet will work, if you can find that many.

G-
« Last Edit: July 05, 2005, 08:31:11 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #17 on: July 05, 2005, 12:20:48 PM »
I wound it with 150 turns per tooth making 900 turns total for the entire stator 150x6=900.


Like I said, I don't know much about this stuff yet, but read that if you want more juice you need more turns and stronger magnets......


Got any ideas about what this thing would produce, considering that the entire stator is wound in series for voltage/amperage/wattage if I got rid of the 6 magnets and redid the rotor using 4?

As I've said in probably a 15 mile an hour gust(exact speed unknown) my multimeter shows 13.X volts DC...and that should be enough to give some unknown amount of charge to a 12 volt battery


After all it'd be nice to be able to get away "without" having to build a rotor, and as you've said these fan blades work pretty well all by themselves.....


I've just found out via experimenting that using another lakewood box fan as the wind, that on "high" if I give it just enough bump to make it past one cog, it'll spin up and eventually shows 12.3 volts DC on my multimeter......But it needs to be within about 1 inch of the other fans cage.....

« Last Edit: July 05, 2005, 12:20:48 PM by ZooT »

Norm

  • Hero Member
  • *****
  • Posts: 1841
  • Country: us
  • Ohio's sharpest corner
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #18 on: July 05, 2005, 09:37:58 PM »
 It wasm't a box fan conversion but I remember

....I think it was TomW saying that he hooked a

switch to the battery so he could energize one coil so he could kinda bump start one that cogged

badly...it didn't matter if it started going in

the other direction because it would go to the

previous cog and bounce back in the right direction and with the wind trying to turn it in

that direction ...it would get over the hump and

start spinning....something like that...anyway it

worked.

                   ( :>) Norm.
« Last Edit: July 05, 2005, 09:37:58 PM by Norm »

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #19 on: July 06, 2005, 12:38:43 AM »
Tomorrow I'm going to try, just as an experiment, adding some duct tape "blade extenders" to the existing fan blade and see if it'll spin up by itself in front of the other fan......

« Last Edit: July 06, 2005, 12:38:43 AM by ZooT »

Norm

  • Hero Member
  • *****
  • Posts: 1841
  • Country: us
  • Ohio's sharpest corner
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #20 on: July 06, 2005, 05:48:25 AM »
....adding some duct tape

......don't forget the Bondo!

         Joking!

             Have a Fun Day!

               ( :>) Norm.
« Last Edit: July 06, 2005, 05:48:25 AM by Norm »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #21 on: July 06, 2005, 08:12:59 AM »
ZooT,


If you go to 4 mags, you MUST rewind the stator.

Or half your voltage is one way and half the other way, so nothing will come out.


The 1 x 1/8" neos are kind of thin. Doubling stacking may help.

Magnetic flux is past my expertise, so I just use the biggest that fit. :)

And a 3/4 x 3/4" x 1/4,  or  3/4 dia x 1/4" would let the air gap be a little smaller.


Maybe it could go to 4 bigger magnets,

and reconnect the coils like I did,

and wire it in star / wye.

Pure speculation.


I got a $10 digital wind gauge from Radio Shack. 6MPH is the lowest it reads.

Before that, I would have guessed a 8MPH wind was 15MPH. Maybe thats just me.


Zubbly told me, for 6 magnets and if the rotor is still round,

to to move #2 and #5 a little clockwise,

and #3 and #6 a little counter-clockwise, to reduce cogging.


Just tested my 'Lakewood' or one that sure looks like one.

Old style rounded blades, not the newer, almost pointed blades.

On high, right against the grill, is 13MPH.  2" out is 11MPH.


Someone said with a good PMG and good 20" blades,

a output of 40 to 50 watts could be had.

That's why I was quite happy to see 30W at 1100RPM,

with very little effort, tools, or money.

(I have about $5.50 in this whole thing, including epoxy)


Windstuff Ed's blade program shows a 20" blade can make 37W in a 28MPH wind.

But I don't think the fan blade will. Mine stall unloaded before 20MPH.

It is $5 well spent.

The other programs I tried don't work right below a 1 meter blade diameter.

iFred has an in depth explanation for Ed's program.


I think my 'good' 20" fan blade is 'making' 20~25W,

but 65% is lost in the high resistance coils.

Have to get back to that one of these days...


Sure wins the ugly contest!





G-

« Last Edit: July 06, 2005, 08:12:59 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #22 on: July 06, 2005, 08:18:36 AM »
Not sure if that would work every time on a single phase.


(I'm getting bold with these photos Norm.

Even posted the ugly one!

I'll probably regret that later.)


G-

« Last Edit: July 06, 2005, 08:18:36 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #23 on: July 06, 2005, 10:28:40 AM »
Duct tape?.....bondo?


Heck.....I'm going to bungee cord a tower together and use baling wire to wire the generator to it's mount and maybe stick the tail on with a booger*LoL*


But seriously folks, like I said before this is just a "fun" project......yet if I can produce some useful power(enough to charge a 12 volt trolling motor battery)it'll slip from the "fun category" to the "useful and productive work" category........

« Last Edit: July 06, 2005, 10:28:40 AM by ZooT »

veewee77

  • Full Member
  • ***
  • Posts: 244
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #24 on: July 06, 2005, 10:39:19 AM »
There's only two things you need in the toolbox, anyway.


Duct Tape and WD-40.


If it moves and shouldn't, Duct Tape it!

If it don't move and should, WD-40 it!


Doug

« Last Edit: July 06, 2005, 10:39:19 AM by veewee77 »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #25 on: July 06, 2005, 11:15:35 AM »
« Last Edit: July 06, 2005, 11:15:35 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #26 on: July 09, 2005, 10:07:31 AM »
maybe three magnets?

That should allow the same sort of flow as 6,...shouldn't it?
« Last Edit: July 09, 2005, 10:07:31 AM by ZooT »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #27 on: July 09, 2005, 08:23:00 PM »
Sort of.

There will only be half the flux of 6, so it takes twice the turns.

And. A big and.  There will be all of the cogging!


With 4 magnets the cogging is almost non existant. I believe that is the "new big idea".

It also allows for some form of 3 phase, even if it kind of inside out.


I think 4 mags is the way to go.

And some type of 3 phase.  I will rewind one soon (I hope) to test some 3 phase type outputs.  I'm not a big fan of rewinding, so it could take a while.

Plus it breaks my heart to strip the highest output little PMG I ever made.


Wish I still had a O'scope to see the waves.

I'm honestly not sure how the output will look.


Did you see this?  Maybe it will help.

Not that I know much more now than I did then, except it does work!


http://www.fieldlines.com/story/2005/5/4/15729/16162


G-

« Last Edit: July 09, 2005, 08:23:00 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #28 on: July 09, 2005, 10:40:22 PM »
Thinking out loud.

Follow me if you can.

You may like this.


Your mags are not that great.

But 31VAC is 44VDC.

And 3 phase star needs 1.73 times LESS turns,

and lowers the effective resistance,

and 44VDC seems kind of high for a 12VDC machine like this.

And you said the cut in is very low.


So,

Lots of guessing, but

I keep getting 240 to 300 turns per phase,

for 4 better neos,

and 3 phase.


You ALREADY HAVE 150 turns per tooth,

thats 300 per phase !!!


So,

it sounds like changing to 4 thicker neos and reassigning the coils (like above) on the machine you have "could" be a very workable idea!


Testing just 1 coil would prove a lot. 4 magnets would be better I think, but 6 should work for a single coil test.


I have been wrong before. Just ask my wife :)

But your setup really doesn't work now and it would be kind of easy to try.

And I had an incident involving a microwave transformer, my thumb, and plenty of blood, so I won't be rewinding anything for a while.

G-

« Last Edit: July 09, 2005, 10:40:22 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #29 on: July 12, 2005, 10:11:54 AM »
I wound the stator in one continuious loop all the way around so do I even have phases?

From my unknowledgeable line of thinking I'd think that 6x150=900 turns and a single "phase".......there's only two leads


I know you wired yours as three seperate phases of three coils each, but mine goes all the way around with the leads coming out of number 1 coil and number 6 coil.


Anyways.....yesterday a guy was cleaning the street with a leaf blower...and just for "whatever" I asked him if he'd give the genny a blast.

The leaf blower said on it's side "70 mph" and the genny produced 26.x volts DC at 70 miles an hour but was trying real hard to torque out of my hand at that speed.


Again though I've got to ask.......if I were to build a three blade prop either out of 1/8" plywood as per that other thread here or a 4 foot Zubwoofer design would that generate enough torque to get this thing to spin up?

Or would I be better off building a rotor similiar to a water pumping windmill looking for startup torque rather than super high revs?


You've called your box fan blade your "high torque" blade, and with the cogging I'd think I need torque to get the thing spinning rather than speed, assuming that it spins fast enough to generate the 13 volts or so required to put some charge into a battery......

After all, once it starts it'll continue to spin even if the wind drops way down....It's just getting the darn thing started*L*

« Last Edit: July 12, 2005, 10:11:54 AM by ZooT »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #30 on: July 14, 2005, 02:09:39 AM »
Well,


If you change to 4 mags, you must 'reassign' the coils, then it is 3 phases!

I was figuring for stronger mags too.

The 3 phase will increase how effective everything behaves.


I am the very last person to ask about blades!

My plastic box fan blades work great for low rpm, high ohm, many turn alternators.

My 'just like they said' Zub-Woofer blades are great for normal speed alternators.

A 15 to 30 blade may do OK, but I have decided that is not a great way to go.Ever.


I personally don't think a 6 magnet 6 tooth alternator will be any good unless the average wind speed is very VERY high. Like past 20mph.


example: today we had big wind. Charley, Dave, Elvis, or whatever.

Big, really big, bad cogging, stepper motor. 4 at 18"Dia 4"PVC blades.

Low torque, rarely self started.

The 20" box fan blade would have been great for starting, but the top speed would not have got up to charging speed for most well designed wingmills.

TSR, touque, and diameter must balance somewhere. I don't know where.


Following this could help...

http://www.fieldlines.com/story/2005/7/14/42640/9511


G-

« Last Edit: July 14, 2005, 02:09:39 AM by ghurd »
www.ghurd.info<<<-----Information on my Controller

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #31 on: July 25, 2005, 10:16:44 AM »
Well I whipped up what other folks wouldn't, but I would call a two blade four foot rotor and during one especially strong gust here it actually started up by itself*grin*


Now if I could just get "a bit" more oomph out of the rotor I think I'd have this problem of mine solved.

Do three blade rotors provide more "oomph" in the startup department?


And BTW.......I did get just a mite scarey holding the genny in my hand with the blades spinning fast enough that they looked like a blurr........


Later today I'm going to build a cap with a bolt welded on the end for a piece of one inch thin wall electrical conduit so the  bottom point on the arc of the blade is a few feet over my head for further testing.


Hopefully some pics will show up below......










« Last Edit: July 25, 2005, 10:16:44 AM by ZooT »

ZooT

  • Full Member
  • ***
  • Posts: 187
Re: New Idea Makes Box Fan Conversion Very Easy
« Reply #32 on: July 25, 2005, 10:46:33 AM »
I forgot to mention that the blades are made out of 1/4" clear poplar and that I planed a "sorta airfoil" on the back side.


If I can get either this prop or a three blade of similiar design to work to my satisfaction, I'm planning on finishing the blades with "monocote" which folks use to skin balsa airplanes......

« Last Edit: July 25, 2005, 10:46:33 AM by ZooT »