Bearing question

[garfish]

Need some help with knowing what type of bearings to use. I am trying to build a wind sculpture that will have a central fixed shaft (maybe 6-8' of nominal 1" O.D. steel pipe sunk in concrete perpendicular to the ground). Above a bottom non-rotating 4' base sleeve over the shaft, I’ll slide on separate lengths of sleeves of 1.5" nominal O.D. steel pipe over the vertical shaft. The balanced outriggers welded to the sleeves will have various shaped ‘catchers’ for the wind. The sleeves turn in opposite directions. I live where the wind really blows.

So there is my problem: there has to be ? a bearing or a bushing at the bottom of each sleeve to allow the sleeves to turn this way and that. I looked in the McMaster-Carr catalog (www.mcmaster.com) and wow are there a lot of bearings. The load is down/perpendicular, so a Thrust bearing? How about that ultra slippery plastic/nylon/PTFE as a bushing or a flanged sleeve? One fellow told me he used radial ball bearings, but I can’t figure that out because the load is not radial. The weight would rest on the journal? Any ideas are appreciated. This is the heavy duty version of those copper wind sculptures you see turning at the garden shoppees .

garfish

[Mike W]

I use old throw-out bearings from a manual transmission clutch fork. Even when they are too noisy for a truck they still work. I use Ford because that is what I drive. I pull them out of the cast housing and cobble up an adapter for what I need to fit them on. I have two on a 20 foot swinging gate.

[tooldude56]

I am not sure that I am following you 100 percent,but a standard electric motor type sealed ball bearing should work fine work fine,especialy if the weight is under a few hundred pounds,but they can get a little pricey,especialy in the larger sizes.When you figure out what you need for bearing ID. and OD.,email me and I will look to see if I have what you need,because I have quite a few misc. ball bearings.I also have some of the UHMW {nylon type material},but I dont think that it will allow your project to rotate freely enough.HMMM.........MIKE W has a good idea with the trow out bearings too.

tooldude56

tooldude@chartermi.net

[TJJ]

garfish,

How about checking out some boat trailer wheel bearing sets at wally world. They're pretty cheap. Would have to rig up a weather shield. Maybe an inverted plastic cup or cap of some sort slid onto the vertical tube.

If you want a sealed bearing just go to the local bearing house with the ID and OD bearing you need and ask for a light duty angular contact single row bearing (sealed).


tjj

[BadDog]

Axial load ball bearing (like used for caster pivots) or tapered roller bearing. Tapered roller bearing would probably be the best since it is self centering and easily found used in automotive applications. Maybe get some wheel bearings or something where they were replaced due to pitting or something but were not completely shot. 4x4 front hub bearings, full float rear axle hub bearings, something like that. They will have a fairly large inner race and could easily handle the chore, though sealing and longevity might be an issue depending on environment and mounting.

[walker]

Easiest way to do it is to not use a bearing. Use an inner shaft with a pointed end and put a bearing surface on the end of the pipe, a heavy copper cap works fine. Slide the copper sculpture tube over the shaft with a little oil on it and it will work fine. Look at the Whirlybird attic ventilators in the hoime store, the non power ones, they work the same way.

[BadDog]

I think those whirleys do use bearings to keep the bottom located, but been a long time since I really looked at one.

And in any case, I don't think that will work since he needs to stack counter-rotating assemblies.

[enlpck]

Two comments:

1) Iv'e built weathervanes where the rotating portion is mounted on a pin inserted into a hole bored in the top of a solid shaft with a large ball bearing ball dropped into the bottom of the hole. For a light load this works well. Bore the hole to a few thousandths clearance on the shaft, fill with a medium weight oil befor inserting the shaft, and shield to keep out water (I've used film cannisters. Hole in the bottom to fit the shaft, seal with silicone, open und over the lower support, but not touching for free movement) Heavier loads, bore larger at the top end to allow smaller ***** to be dropped in and provide lateral. support.

2) Examine the sculptures of Susumu Shingu (_Gift_of_the_Wind, _Echo_of_The_Waves_, etc) for ideas. Descriptions are in Schodek, D.L., _Structure_in_Sculpture_, Ch 7 and appendix 1, among other places. Shingu used roller bearings, tapered and straight, in several works, with good life and performance. Some required an oil feed (I believe in part due to proximity to salt water, but also due to heavy loading. Some of his work is BIG. If you ge to Boston, check out Porter Square red line station, and the wharf area near haymarket, whatever they renamed it this time.) but for lighter stuff, shielding and grease should be sufficient.

You may find junkyards a good bearing source (front ends, rear ends, transmissions, etc) motorcycle scrappers are also quite useful (an aluminum wheel cut down on a lathe has a marvelous bearing set for radial and axial loads, already mounted on a shaft)

I don't think your major load will be down. The wind load will be the big issue, and you will want to consider the cantilever loading on the post base, the lateral loading at the base and on the arms, the centripetal load at the point of attachment for the rotating arms (can be quite significant at moderate speeds), as well as, possibly, methods of feathering in extreme wind.

If you have a local windmill supplier, you may want to talk to their engineer.

Also, for small work, roller blade bearings are cheap and tough. (6mm bore, 22mm OD, I believe)

[TOMWELDS]

You could use a thrust bearing, but you will have to fabricate a washer on the sleeve and on the shaft for it to ride on.

[LBHgti]

Go get a front hub and wheel bearing off a front wheel drive car. These bearings are as stout as they get and sealed against the elements. On the car, they are subject for forces from every direction so they should work fine for your application. Then you can weld whatever you want to turn onto the hub.

[hankj]

Go to www.use-enco.com and search for "bearings". They have a ton of 'em, and for good prices. I used a pair to fix the neighbors windmill - $6 for two sealed, steel ball bearings.

Hank

[garfish]

Thanks for all the good ideas for and about bearings. My local library has the Schodek book ! and I'll get it this afternoon. Here is a guy that does some very interesting work resembling what I hope to pull off ,Cosmic Steel .

[Mike W]

Interesting, what does that stuff sell for? He doesn't seem to be a big believer in paint.

[LBHgti]

He had one in there for $19,000 !!

[toolaholic]

he'll be sneak in the dump at midnite with a wheelbarrow again. the judge said one more time and it,s stony lonesome for mike the artist!