Wind Sculpture, Vertical Axle, Bearings

I want to make a wind sculpture of the variety what pivot around a vertical axle as the wind blows. Examples of such sculptures are
shown here:
http://www.copperwindsculptures.com /
The issue I have to overcome is the ground mount - mounting it to the ground in such a way that it can rotate.
The art part of the project is not a problem - but the mechanics involved to get the sculpture to rotate on an exis is a problem!
I have found mail order suppliers of tubing and bearings, however, as this is a bit new for me, I am dis-inclined to simply order materials without more knowledge.
Although not fixed on the idea I was thinking of something like the following:
Narrow pole cemented vertically into ground. Rotating Sculpture which is on wider pole is slipped over narrow pole. Suitible bearings are in place between narrow pole and wider pole so that friction is negligable.
Anyone have any ideas: a) Supplier of such poles so I don't need to design it. b) Develope knowledge so I know what tubes to order, which bearings, and mounting brackets so the whole thing goes together.
I would be greatful for any ideas.
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^^^^^^^^^^^^^^^^^^^ Go to a wrecking yard--oh, sorry--auto dismantler, and buy an axle with the wheel bearings and brake drum intact. You can stand the axle in the ground in concrete and either mount or hang the sculpture from the brake drum. If you use a front axle, of course, you will have to weld the steering linkage so the spindle stays vertical.
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Leo Lichtman wrote:

Good idea, a number of FWD cars have bolt on rear stubaxles, VW for sure so you could bolt that to a tube/pipe of the required length with a suitable plate welded to the end.
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On Wed, 18 Jun 2008 16:29:25 GMT, with neither quill nor qualm, "Leo

I was thinking about that, too, but he could simply set the back of th spindle and steering arm into the cement base. It could go a decade without lubing, I reckon.
-- The only way not to think about money is to have a great deal of it. -- Edith Wharton
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    And with the rear axle, you'll probably want to remove the other half axle and shaft, and the input pinion so you don't have them thrashing around in the ground. You'll probably want to keep the spider in place to act as a guide for the lower end of the half axle shaft.
    Not sure what you will need to do to keep water out of it, especially if you are setting it up where there is a high water table.
    Good Luck         DoN.
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"DoN. Nichols" wrote: And with the rear axle, you'll probably want to remove the other

^^^^^^^^^^^^^^^^ I would favor a rear axle from a front-wheel-drive car. None of the problems you are worried about.
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On 19 Jun 2008 04:21:29 GMT, with neither quill nor qualm, "DoN.

That's where the steering knuckle and brake rotor, complete with seals, would be more handy.
-- After all, it is those who have a deep and real inner life who are best able to deal with the irritating details of outer life. -- Evelyn Underhill
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On Wed, 18 Jun 2008 11:53:43 -0400, with neither quill nor qualm, snipped-for-privacy@bellsouth.net quickly quoth:

You have two (well, 3) forces:
1) lateral, wind pressure from the prevailing wind, 2) axial, from the weight of the object (aka "gravity") and 3) chaos, twists from the buffeting of the wind.
(A _real_ engineer can give you details on those. ;)
Loads 1 and 2: Since you'll likely use 3/4" ID and up to 2" OD bearings, most any bearing will work for your purposes without disintegrating from overloads.
Load 3: This errant load makes you design the sculpture to keep the thing from flying off into the wind. It looks like this guy in your link used setscrews to mount the bearings in the tubes, and he probably pressfit the IDs. Woiks for me.

Ah, you're a real _wildcatter_, I see. <chortle>

Could work. Use a standard ball or roller bearing on the bottom and a tapered roller on the top.

Just match the shaft to the inner bearing diameter and the outer tube to the outer bearing diameter. It looks like this guy used setscrews to mount the bearings in the tubes. Woiks for me.
Did you see the movie "Twister"? That woman could design spinners! (I'm sure the actress did it because works on the site featuring the artist Evan Lewis' work is nothing like the beautiful sculpture in the film. :/ )
-- The only way not to think about money is to have a great deal of it. -- Edith Wharton
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It seems you might be a wood worker. Have you thought of plain wood-and-iron bearings?
Bob Swinney
quickly quoth:

You have two (well, 3) forces:
1) lateral, wind pressure from the prevailing wind, 2) axial, from the weight of the object (aka "gravity") and 3) chaos, twists from the buffeting of the wind.
(A _real_ engineer can give you details on those. ;)
Loads 1 and 2: Since you'll likely use 3/4" ID and up to 2" OD bearings, most any bearing will work for your purposes without disintegrating from overloads.
Load 3: This errant load makes you design the sculpture to keep the thing from flying off into the wind. It looks like this guy in your link used setscrews to mount the bearings in the tubes, and he probably pressfit the IDs. Woiks for me.

Ah, you're a real _wildcatter_, I see. <chortle>

Could work. Use a standard ball or roller bearing on the bottom and a tapered roller on the top.

Just match the shaft to the inner bearing diameter and the outer tube to the outer bearing diameter. It looks like this guy used setscrews to mount the bearings in the tubes. Woiks for me.
Did you see the movie "Twister"? That woman could design spinners! (I'm sure the actress did it because works on the site featuring the artist Evan Lewis' work is nothing like the beautiful sculpture in the film. :/ )
-- The only way not to think about money is to have a great deal of it. -- Edith Wharton
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Don't use ball bearings.
Approach the problem like a gate or a door.
The top bearing should deal with the downward force of gravity. It this case would be thrust. The lower bearing should deal the the sideways load.
Use a pointed bar and a socket for the top bearing (good support, minimal friction)
Leave a space between the outer tube and the narrow pole, so they wont rub on each other.
For the lower bearing use a bronze washer that just slips over the narrow pole and rotates freely and attach it to the tube so that it centers it over the pole.
Paul K. Dickman
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As a kid I made windmills for the garden to tumble perhaps half a pound of rocks and scare the birds off. The shafts were nails and the pivot bearings were tin can steel, dimpled for the thrust bearings and punched through for the others, which gives more surface area than drilling. Typically they lasted three months out in the weather and failed for reasons other than bearings.
More recently I've made outdoor bearings out of hardwood boiled in paraffin wax running on stainless steel bolts. They were large- diameter clothesline pulleys so the load was occasionally high. They lasted for several years completely exposed to dust, rain and ice and the bearings were still in good condition when the glue joints failed. The wood was scrap mahogany (?) from a casket maker.
It's worth considering the very cheap flanged ball bearings used in lawnmower replacement wheels. The flange and their tapered outer housing makes them easier to mount and the large internal clearance lets them run despite dirt and rust. The shaft can be threaded rod with a nut on either side.
Two of them hold up the 100+ Lb head of my sawmill. I tested them at 200Lbs each. You can mail-order them for less than $1 or pop them out of the wheels.
Don't just hang the sculpture from the pivot. If a strong wind bends the support enough it could be blown off upwards.
Jim Wilkins
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Jim sez:
", , , More recently I've made outdoor bearings out of hardwood boiled in paraffin wax running on stainless steel bolts. They were large- diameter clothesline pulleys so the load was occasionally high. . . . ."
It is good to see Jim's endorsement of wood bearings. Wood opens up a whole 'nother realm of consideration for the home shop craftsman of limited means (most of us). Wood and iron formed the bearing pair for a lot of early steam ship propeller and shaft bearings.
Bob Swinney
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Those bearings were lignum vitae, which Home Depot doesn't carry. They do have maple dowels, though. I built a model water wheel in college almost entirely out of wood, with lantern-wheel gears and shafts made of maple dowels. It was a protest sculpture that sat outdoors in a smelly eutrophied stream pretending to meter out little scoops of Clorox into it (the jug held water).
Except for clearing off the ice and replacing one broken gear peg it ran pretty well for a month until some frat stole it. By then it was green with algae and I didn't want it back.
The stream ran under the biology building. When they analyzed the water they discovered that phosphorus runoff from the athletic fields was feeding the algae. That was in 1965.
Jim Wilkins
There is a reconstructed water-powered vertical saw mill near here with its power transmission cobbled together from old factory parts and much wood. Many of the bolt holes have opened up from the constant back-and-forth thrashing.
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In article

Actually, maple dowels have become hard to find. Mostly they claim only to be a "wood dowel", wood species unspecified. I've been told that they are probably luan, which would make for very weak dowels. They certainly feel lighter and softer than maple.
Joe Gwinn
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On Jun 18, 10:53 am, snipped-for-privacy@bellsouth.net wrote:

Go to the junk yard and purchase several bicycle frames. Cut em up and use the bearing hubs, weld them to the proper poles. That's where I would start. Great opportunity to learn how to weld.
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