Treadmill Motor PVC Blades

[packman1234]

CmeBrew

Thank You...

I'm headin downstairs to cut the five per your suggestion...This is sooooooo... frustrating!

When I loosen the allen screw, it spins much better with less resistence(Just freewheeling on the shaft) I guess this is a good way to balance these also...Though I dont know what kind of weights to use on the hub or the blades for that matter!

I suppose I will have to redrill the hub now for for a five blade configuration.. Do you know what degree i would use for the 3" cut?  The last ones I cut two 150 degree sections with a 60 degree leftover. Then I drew a line for the tip at 1.5inches on both pieces of the 150 degree sections which made 4 blades. Would I use the same setup?Or.. do I cut the 6inch into four 90 degree pieces?

Any help is appreciated.

Bob

[CmeBREW]

Well, what I do is make a posterboard blade template and trace it on the pipe and jig saw it out in a few minutes.  I made my blades similar to yours with the bottom (trailing edge) straight all the way down to the tip. It make it easy to make them the same.  

Here's a picture of my last pvc blades:

Maybe make the blades about 2" wide at the hub where it screws down.

It is up to you how well you sand the edges down. If you don't make the "Magnetic Decogger" you might want to make the blades 3.25" at the widest point instead of 3".

Thats a good idea about balancing them on the shaft with a little oil.

It is easiest to have a postal weight scale to weigh each blade as you make them, to get them all exactly the same weight.  5 blades should be even easier to balance.

If they are off balance, I just tape a 3/16" little bolt/nut and washers to the blade up near the hub to which ever blade is off, and when It balances, I then drill thru the pvc blade and bolt the # of washers in that location.

I don't know where you live, but summer is not so good for smaller mills around here. The winter is quite good though.  Where I am at in Ohio, my solar panels probably do on average TEN times more daily watt hours than my 6 foot mill in the summer time-- BUT my 6 foot mill probably does TEN times more average Watthours than my solar panels in the winter months!  It completely reverses. In the spring and fall they seem to be about equal.

You might think about getting solar panels ASAP.  (or a 10 foot hawt 40 ft in the air! ha)

-Good luck.

[packman1234]

The pic of your blades look like they were made out of 4inch pvc...

Thats my problem now.....4inch or 6 inch? It's the angle part I am confused on.. I am VERY grateful for your help, but you are not really answering my questions... 4 inch cut into four 90 degree pieces...or  .....

4inch cut into two 150 degree and a 60 degree leftover??

Maybe you are not understanding how I made the first set.............http://www.thekevdog.com/projects/wind_generator/    This is the part I need to know!!

Thank You SO Much..

Bob

[CmeBREW]

Yeah, it is 6" pipe.  I like 6" better since the arch is bigger which means less blade hangs over with the width up near the root. But some use 4".

Sorry, my Geometry is not so good.  That link goes to his front page but it keeps going blank for me??  I just do it the simple "Caveman" way.  Maybe someone else will understand the angles and comment.

If all else fails, it would make a nice Ped generator I'm sure for excersise and 30-40 Watthours.  (Thats what I am making right now)

[wooferhound]

How to make a PVC blade to the specs CMEbrew stated, will be 25º at the root and 7 degrees at the tip

draw a line down the length of the pipe. putting the pipe in a doorframe makes this easy.

At the root measure 3 inches around the curve of the pipe and make a mark.

At the tips measure 1.25 inch the same direction as in your first measurement and mark it

now draw a line between the 3 inch mark and the 1.25 inch mark.

now cut the prop out using the 2 lines you just made

Here is a plan for a  prop with 2 blades made from a single piece of pipe. Look at the angles and you will see the 7 and 25 degree points, which for 6 inch pipe is 3 inches at the hub and 1 inch at the tips. Hope that helps you, and here is the story the plans came from...

http://www.fieldlines.com/story/2003/11/11/172721/53

[packman1234]

Woof

Does this link work for you?  http://www.thekevdog.com/projects/wind_generator/

I think the pic you show is the angle on the edge of the pipe AFTER it is cut. I still need the angle from the link for the initial cut. The link shows 150 degrees. Then the 150 degree piece makes 2 blades.

This is where I'm stuck! He states anywhere between 75 and 150 is where you want to be...but the first 150 I did created a 6inch root that was too much of a drag(I think).

I wish I had better math skills!

Thanks for the help

Bob

[wooferhound]

I'm not sure about that design. I see that a single PVC piece 150 degree pipe makes 2 blades, not quite sure what that angle ends up being doing that. If a single blade ends up being more than 45 degrees then it is counter productive. I personally would follow CMEbrew's suggestions for measuring the pipe. I'm at lunch from working right now, will try to respond better this evening.  

[wooferhound]

Home from work . . .

I'm going to steal the drawing off of that website and refer to it.

Using 6 inch pipe I would cut a section out of the side that is 4.25 inches wide, the small inset drawing that says 150 degrees would be replaced with 4.25 inches.

On the larger drawing of the marked pipe on the lefthand side. Replace 1.5 inch with 1.25 inch. this will leave 3 inches on the other side of the mark.

Do the same thing on the other end of the pipe piece but in reverse. Then draw a line between the marks. A tape measure turned up-side-down and laid down onto the pipe makes this very easy.

Now cut the pipe along the line you just made. The result is two PVC Pipe props with 3 inches around at the root and 1.25 inch around at the tips. The extra cuts at the hub that are shown on the drawing are not necessary, That is more for looks but, it cant hurt it. The props will be about 25 degrees at the hub and and 8 degrees at the tip.

For bonus points you could round off the leading edges and sharpen the trailing edges.

Hope that clears it up a bit . . .

[farhan]

This is a good way of making PVC Blades, Thank you for it. Earlier how i learned and made my PVC blades was cutting the the 6 inch pipe into 4 equal pieces first and then leaving 1.25 tip from one side cutting to the next. Looked same as the ones you just showed but more cutting involved.

What is the length of this 6 inch pipe you took?

Thank you for your guidance.

[packman1234]

Thanks Woof

I made several more blades and tried the whole thing in the driveway where there is more wind. I can get the thing to spin if it freewheels on the shaft. As soon as I put the key back in, it wants to start..but just cant do it.

I converted the original diagram on how to make these to 112.5 degrees and have 4inches at the base and 1.5 at the tip(Tried it only with 3 blades)They are 36 inches long. The wind stopped shortly after cutting these and dont know the results yet.I am positive that your help is working....

The conversion you gave me came out to 80 degrees and those spin also without being connected to the shaft. I feel like a mad scientist out in the driveway as a lot of neighbors stop by and ask just what in the hell I am doing!! They keep telling me the blades need to be wider to capture more wind and one suggests I lessen the spring tension on the brushes and see what happens.

The 112 degrees is a compromise between yours and the originals and I hope it spins soon! Another neighbor stopped by and told me he has been tinkering with one and will share his results with me.

How exactly do I round over the leading edge and which side get sharp on the trailing edge?

Again....Thanks for the great help!!

Bob

[farhan]

If i connect my treadmill motor to a 12v battery it gives out about 400rpm, when i connect to 24v it gives out 900-1000rpm. Its a 180v 4000rpm turdan treadmill motor.

I wanted to ask this that does the same happen when i will use it as a wind turbine? i mean if it gets 400rpm from the wind it will produce 12v nd same for 24v?

[ghurd]

Pretty much.

It takes a hair more RPMs, but that's the idea.

Then as it spins faster the charging amps increase.

G-

[farhan]

Ok thank you, so is this motor worth trying as a turbine?

I did but it wouldn't produce 12v constant, produced 7-8v but in a good wind went to 16v too, flux told me to gear 2:1, i'm making that right now.

[packman1234]

Firhan

How do you know you are getting 400rpm when connected to 12v power.. Thats the part I get stuck at..

Bob

[farhan]

I bought a digital tachometer and from that i calculate the rpm, i know digital tachometers readings are not perfect but good for an idea. Take 3-5 readings and take an average. Thats what i do, don't know if its the best way or not : )

[adaml]

packman,

How did you get on with your pvc blades in the end.  What size did you settle on?  This is exactly the same thing I am struggling with now so appreciate your frustration at the time!  Good Luck!

[packman1234]

Adaml

I made the blades 36" long and 3.5" wide at base and 1.5" at the tips.. It's up and flying and I have a lot of testing to do still..

Bob

I'll upload some more pics..