Small VAWT: what bearings to use?

[JeroenH]

I want to build a small VAWT, I would like to start with a savonius en if that works out I might have a go at a darrius. Anyway, I have lots of R/C modelling experience so I'm not afraid of woodwork and some light metalwork. But what I can't figure out is this: where can I get bearings for a wind turbine? The first attempt will probably have a 5 or 6mm axle but I have no idea where I could get bearings.

I would be more than happy with something in the range of 5..10 Watts @ 12V, any ideas on how big I should make things? Diameter/height? How many magnets & coils to use? How many windings in a coil? Wire thickness?

Thanks in advance!

[Dutch]

The size of the bearing for a VAWT depends on the design. You can use two bearings, one at the bottom and one at the top, or just one single bearing at the bottom. When you use a single bearing it has to be a strong one. I prefer the design with a single bearing and I am experimenting with it. You can see some pictures on http://www.windwerk.nl under 'Zelfbouw'. I used for these windturbines the bearing of the back wheel of a Fiat Panda. And this because it's fastened with bolts on the chassis. So it's easy to get one.

But you are working on a different scale. I suggest you use the bearing of a washing-machine - the type that has only one single bearing. They are cheap and easy to get - new or second handed.

Succes.

[wdyasq]

Rollerblades and skateboards have nice small bearings.

Ron

[baggo]

Computer hard drives contain some very nice small bearings in the disc and head assembly. You should be able to get plenty of scrap ones to salvage the bearings from.

John

[JeroenH]

Yeah I saw your website - nice Darrius!

I think maybe car and washing machine bearings are a bit too big for want i want to make.

A question about your Darrius though: do those 4 blades have a fixed angle of attack, or is there some pivoting mechanism?

[JeroenH]

Thank you!!

I was just gutting an old double-height SCSI hard drive to salvage the magnets, and had already thrown away the casing and the arm mechanism. Stupid of me! I retreived it from the garbage bin and you are absolutely right: the arm mechanism has two very smooth bearings which look like they perfect for what I want.

No why is everything in a hard drive fixed with those weird and annoying torx screws. I had to drill every last one of them because I don't have a torx driver.

Question: I now have 4 extremely powerful magnets. They have a concave shape. Only I cannot tell the N and S poles. Where would they be?

[JeroenH]

As you are from the Netherlands also: do you know where I could get insulated wire for winding coils?

[TomW]

JeroenH;

 Only I cannot tell the N and S poles. Where would they be?

That would be because most HD mags have the N and the S pole on the same face.

Cheers.

TomW

[JeroenH]

That would be because most HD mags have the N and the S pole on the same face.

Ahhh that would explain a lot. Are these magnets useful in an alternator?

[Norm]

 Replacement ball-bearings for roller blades ...got 16 of em for about $4...(5/16 shaft)

Clearance sale at Wallymart (lowering prices everyday(only on things that aren't selling))

  So ...one time offer only --- 2 bearings for a $1 plus postage ---limited supply only 8 left..at this price....E-mail me if interested.

....but my favorite will always be a front bicycle wheel a nice smooth grooved tread design and friction pulleys on a bunch of small hobby

motors all around the perimeter wired up in series or parallel ....depending on circumstances.. Fun just thinking about it. try it..You'll like it ..

               ( :>) Norm.

[Jessum Dumguy]

Funny but I was wondering about bearings some

lately aswell, I'm sure the inline skate bearings

would work well given the scale of the project.

Heres A place or two I found in short order with Google

http://www.edsbearings.com/

http://skate-buys.com/inlinebearings.html

http://www.vxb.com/miva/merchant.mv

 And of course theres always

http://search.ebay.com/inline-skate-abec-7-bearings_W0QQsokeywordredirectZ1QQsonewuserZ1

[Norm]

 Jess..........,

     Thanks for the link

http://www.edsbearings.com/

   would have been sufficient, it was a real eye-opener....you know, even on a large scale a savonius...it seems to me that the bearings would hold up fairly well a set of bearings for each stage on a multi-stage VAWT with blades about 2x4 ft.  according to the Q&A cheaper (abec3 rating) would maybe be even better...as they would last longer

    As far as I was concerned it was very interesting and informative reading. Thanks Again

                 ( :>) Norm.

[Jessum Dumguy]

Only Problem I see with using them in a

VAWT would be that the bearing is designed to

handle the load on the Horrizontal axis not the vertical.

A Cone or Tappered bearing like that of a auto would

handled the weight along the axial better.

Perhaps something from a small car,  I've seen them

in the auto parts store as small as 5/8 inch I.D.

They can probably be found smaller.

Maybe use a axial bearing for a

lower ( weight bareing ) and smaller bearing like

these skate bearings at the top to keep it

all straight when the wind blows good.       8^D

My need is for a horizontal axial so

these inline things will work great.

[hvirtane]

I would suggest using the pedals' bearing from

an old discarded bicycle. I mean the one, which

is a part of the frame so that you have to cut

the whole frame in parts.

- Hannu

[JeroenH]

Only Problem I see with using them in a VAWT would be that the bearing is designed to handle the load on the Horrizontal axis not the vertical.

I think you are correct if it would be a larg(ish) turbine, but at first I want to start small. It doesn't even have to last long, it's just experimental.

[elvin1949]

crankset bearing's

later

elvin

[Ungrounded Lightning Rod]

I think you are correct if it would be a larg(ish) turbine, but at first I want to start small. It doesn't even have to last long, it's just experimental.

Remember that on a VAWT the tip speed is proportional to the wind speed.  So smaller turbines have higher radial forces on them from their spin, in inverse proportion to their radius.  (Like a car at a given speed taking a wide or a sharp curve.)  A smaller turbine has to be stronger than a larger one or it flys apart.

That's mainly an issue for the prototype's structure.  But there is an issue for the bearings:

Faster spinning means more viscous heating of any lubricant.  It also means more wear (though wear is reduced by the lowered load forces).

Wearout shouldn't be an issue for a short-term prototype, but you'll have to deal with it for a more permanent instalation.

(I'd be inclined to go with automotove bearing systems for a working mill.  They've been designed for long life despite heavy loads, far heavier transient loads, and extreme conditions of weather and dirt.)

[Norm]

you can use roller blade bearings for small projects like this they were designed primarily for horizontal loads ...incidental vertical loads and if end thrust is really a concern...drill a small hole in the end of the shaft and imbed a steel ball...a hard steel surface for it to ride on....              ( :>) Norm

[TomW]

rod;

You seem to have ignored the huge rotational forces on bigger units in your above advice concerning bearings. Roof turbine vents spin very fast are wind or rising air powered, are narrow and have no bearings yet last for decades.

Cheers.

TomW

[Jules]

Hi Dutch

Liked the pic - I too am interested in VAWT.  Interestingly, do you have any electrical output specs to your build - or are you, at the moment, experimenting with VAWT turbine builds...

Cheers

Jules

[nack]

I would recommend using sealed ball bearing sets, such as those used in automotive water pumps.  Use sets in pairs, space them as far as possible away from each other for best radial control.  Whatever you use, make sure that it has a way to keep the grease in and everything else out.  The permanently lubed, sealed ball bearing sets will eventually fail as the grease breaks down over the course of many years and bazillions of rotations, but they are cheap enough to make this a pretty good compromise when compared to a non-sealed design that requires periodic lubrication and external oil/grease seals to survive.

[Dutch]

Try this - look under Draad, kabel

http://www.xs4all.nl/~barendh/Indexned.htm

[Ungrounded Lightning Rod]

On a vawt I'd recommend (in addition to everything else) a "slinger".

make a disk of something weatherproof, larger than the bearing, and put it on the shaft just above the bearing.  Caulk it to the shaft really well.

Any rain, mud, or other liquid what-have-you that runs down the shaft or is falling toward the bearing will hit the slinger.  Then the spin will fling it off the slinger to the side.  The bearing will remain pretty much clean and dry.

The slinger will also fling some air outward, so fine dust will to some extent be sucked toward the bearing.  So a slinger is not a substitute for a bearing seal or shroud.  But it does keep liquids out very simply.

[JeroenH]

Thanks for the tip!

[JeroenH]

Update: I am now in the process of building the small wind turbine. It will be a Savonius, with a disc diameter of 28cm and a height of 30cm.

I will use the bearings I got out of a hard drive, and the electricity generation will be means of a geared (7.8 : 1) small electric motor. Both the gears and the motor are salvaged from a PC tape drive.

I am taking pictures of the project, when I have something interesting I will post it here.