Versatile experimental windmill

[David HK]

I am new to the board but readers may find some of my experimental kit interesting.

I am focussing my attention on wind power and thought you might be interested in what I am doing. I have home designed a universal type of rotor hub assembly so that I can begin to play around with a windmill unit. I have attached some JPEG photos and from these you should be able to see how things work.

Basically my hub unit can accommodate 1, 2, 3, 4, 6 and 12 blade options - very useful and allows a quick change of options when experimenting. Also, each blade can be infinitely adjusted from 0-180 degrees either way (left hand prop to right hand prop).The width of blade can be chnaged to suit 50 - 150mm.

From the picture it is direct drive connected to an Ametek 40 volt DC motor and to date I have reached an output of 2.5 volts!







Not sure if I am working the photo upload correctly!

The prop unit contains a lot of inertia and is quick to respond to the slightest wind when 6 blades are fitted. Clearly the shaft turning speed is not fast enough so I have engaged a local machine shop to make up some parts that will allow me to fit the Derailleur gear system from a bicycle onto the rotor and motor unit. Once again I will have a choice of gear selections.

Dave HK

[drdongle]

Rather than using gears use blades with an air foil, you never achieve your real potential with boards for blades. The hub is nice though.

[Norm]

  You really need airfoils insteaad of boards...

too many boards and too large to spin the amtec

fast enough....at 2.5 volts how many rpm was it spinning?

              ( :>) Norm.

[bcd]

with all your ideas you need to get a mini lathe.

save some money.

the bike der idea might be fun.

nice proto.

[Ungrounded Lightning Rod]

Ouch!  There's a lot of bending moment on that rod where it enters the hub.  Make sure it's good and thick - and the hub around it ditto - and keep the hub reasonably large radius to reduce the lever arm.  (Remember there's a lot of BACKWARD force on the blades from the wind.  You have to brace it more for than than for turning forces.)

[Ungrounded Lightning Rod]

I hope that's not aluminum - metal fatigue will break it with time.  Steel is your friend.

[DanB]

looks like fun.  Yes - I'd agree with some of the other  posts.  I'd be careful with Aluminum.  You really need airfoils, not boards.  I've always found it rather tricky keeping the hub on teh ametek tape drive motors, they tend to fall off pretty easily.  I'd probably work with one of those really strong 'tapered' hubs that you can tighten onto the shaft, dont rely on a key and a set screw only.

I edited your story so that the pictures show up by themselves.  To make that work, when writing your story - after you've uploaded your pictures, just hit the 'insert image' option on the right side of your screen and it'll stick the proper html in there for you by itself.  If you want to see how I changed it - and what makes it work, right click on the story and veiw 'page source' and you'll see how I changed things.

Welcome to the board!

[David HK]

Thank you all for the very useful comments. This is my bottom line of starting an interest so I will pursue the next option of adding proper blades and see where that takes me. Will keep you posted.

Regards,

Dave

[richhagen]

Everyone starts somewhere.  You will do a great deal to improve your efficiency with an airfoil on the blade design.  Your flat blades are using drag to push them around the hub.  You can achieve much greater rotor speed from using the lift generated by an airfoil to pull them around the hub.  There is a great wealth of information on airfoils and basic design here.  You can search this board with google for a specific subject.  Like you I started my interest independent of others who shared a common interest.  Then I found this board and have learned a multiple of the knowledge that I started with, not that I am by any stretch of the imagination an expert, but the combined knowledge and skills of the folks who use this site can solve many a problem.  Rich

[steak2k1]

Ditto That Richagen...big time.

BTW: Airfoils are actually fairly easy to make.  If I can carve them with a small hand saw for relief cuts, a chisel and a rasp combination...then anyone can.!

Really helps to have Hugh Piggot's books though.  Excellent explanations of how / why / what on a variety of subjects within the area of small scale wind power.

agreed though...very nice hub. looks like possibly a modified headstock from a lathe..??

stk

[Chagrin]

That hub would require a milling machine with a rotary table to get the holes right. Also, mini lathes can really only handle objects 3" in diameter or less - the swing over the toolrest is even less (about 1.5"?).

[ZooT]

I lay my "psuedo-airfoils" out with a black magic marker and "carve" then with a body grinder with a 36 grit abrasive disk....

And yeah I like the idea of that hub yet wonder whether or not the "spokes" have an undercut so as to lock them in in the event of some really high winds

[hiker]

toss some pvc blades on their..........[make your own]

or talk to jerry--

[wind4Reg]

Nice experimental mill. I am sure you will put some airfoils on it to test with. From reading the replys, a lot of people seem to be concerned with fatigue and whether the hub is aluminum. I say go with aluminum if that is what is easiest for you to use after all this is just an "experimental mill", not a commercial unit or your final design. When you do settle on your final design for your production mill, I am sure you will design it with strong enough materials.

Keep posting your progress,

Reg.

[Ungrounded Lightning Rod]

From reading the replys, a lot of people seem to be concerned with fatigue and whether the hub is aluminum. I say go with aluminum if that is what is easiest for you to use after all this is just an "experimental mill", not a commercial unit or your final design. When you do settle on your final design for your production mill, I am sure you will design it with strong enough materials.

Hear hear!  Metal fatigue is a long-term issue.  Feel free to prototype with aluminum.

Just don't forget, when you're done experimenting, to TAKE IT DOWN (or replace the aluminum parts with steel or something else not so fatigue-prone for the long-term.)  And break it up rather than selling it on E-bay or giving it to a friend.

Unlike steel, which doesn't stress-harden noticably until bent or stretched a significant fraction of its breaking strength, aluminum stress-hardens at even small distortions.  So it WILL stress-crack and fail eventually.

A working mill has a DEADLY amount of energy incarnate as moving mass.  Holes in the house and broken bodies are no fun.  They're also much more expensive than the few bucks worth of power you might get from running the experimental mill "just a couple months more".

[GeorgeT]

I'm new here but beg to differ on the mini-lathe definition as I have two bench top mini-lathes.  Your talking about a "micro-lathe". A mini-lathe can be had from HarborFreight for around $300 with a 3 inch Chuck (Which I replaced with a 4" Chuck), 7 inch Swing and 14 inches between centers.  I have one and it works quite well as long as I take light cuts.  My other benchtop is a 9x24.  Here is a very good link to someone that utilizes a mini-lathe to it's best potential. http://www.varmintal.com/alath.htm

My two cents

GeorgeT

[rajesh]

I SUGGEST TO TO START WITH A PROVEN DESIGN AND MANUFACTURE 4FEET SMALL WIND TURBINE.

THERE IS NO USE INVENTING THE WHEEL AGAIN. LATER YOU CAN KEEP ON MODIFYING AND TRYING NEW IDEAS.

WE HAVE HIGHLY LEARNED RESPECTED MEMBERS ON THE DISCUSSION BOARD LIKE DANB ETC OR I CAN HELP YOU .

RAJESH

[TomW]

Rajesh;

No need to SHOUT. Please press that "CAPS LOCK" key on the upper left of your keyboard before posting.

Thanks.

T