I need a swivel or bearing for a lazy susan style turntable.

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wrote:

to use the weight to keep it spinning.

I tried to go this route. Auto wreckers won't do it and they want a minimum of $250 for the hub off anything. I can buy an entire utility trailer kit for less. But I was hoping to find a nice floor flange (like on single pedestal table) and a center bearing that might work.
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Now I remember. Get a weld on stub axle and hub from Northern Hydraulics. Have the axle welded in the center of a 1/4" plate of whatever size you want. Cut off the axle to pit the hub as low as possible, before welding . Or drill the plate to let the axle go through and then weld at the appropriate height. Drill another plate, or maybe your wood, to bolt up where the wheel would ordinarily go. I think you can find a hub with no studs in it or maybe press the studs out of one that comes with studs. Then you can use long bolts to hold the wheel on the hub. The weak point of all this is that the normal hub diameter is relatively small conpared to the table width, so the table must be pretty rigid. Come to think of it, you could use a regular rim as the base of your table, if that doesn't put you too far above the bench. Four little J bolts could hold a plywood table to the top of the rim. You could fill the rim with shot to raise its inertia. Wilson

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I actually considered using the tire as well. Easy to spin. Unfortunately get the parts used and then welded is far out of my price range.
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snipped-for-privacy@address.invalid says...

perpetual motion machine :-).
But seriously folks, it's hard to find a lower friction coeffecient than a lubricated ball bearing.
I just bought a lazy susan that's a large circle with said bearings and it's rated for 1000 pounds. Readily available at Ace hardwares, or cheaper online if you have other stuff to share the shipping cost.
--
Homo sapiens is a goal, not a description

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snipped-for-privacy@address.invalid wrote:

Think air. Use a regular bearing for centre-ing and an air cushion to elevate. Perfboard with some routed out channels and a regulator. Over a large enough area, you'll be able to move tonnage with absolutely no effort and the regular ball bearing will keep things in place. 10's of thousands of pounds, I tell ya. Four 12" diameter pucks moved a buddy's printing press like it was floating on air...waitasec..it darn well WAS floating on air. You know how they stopped it from moving?
Yup... turned off the air.
btw...the compressor they were using was a 3 HP, 20-30 gallon tank. it wasn't working that hard. You only need a little air to get lift...more air does nothing.
Did I help ya? Huh? Huh?
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know how to

One of these in your desired rating and a little modification and there you go. :)
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You can use a router with circle cutter jig and a round nose bit to cut a rounded bottom circular channel in the top and bottom MDF. Fill channel with marbles. I had made one of these using 3/4" plywood approx. 30" diameter with channel at 24". Can't see why MDF wouldn't work for you. Don't remember MDF being available when I made that top 20 years ago This was a TV rotator. (I use for about 8 years never a problem and very little force needed to turn about 100 lbs. (you could even get the marbles at a $1 store.) This whole project should do the trick and its pretty cheap too. Good luck.

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BlairR,
I may be missing a few appends to your posting, but I still do not have a picture of what you are trying to do.
You want to spin by hand, not turn, a 24" diameter, 4" thick MDF turntable located on your workbench. And you want it to spin this turntable with something unknown on it, at some unknown rpm for some unknown period of time.
Although I've seen a number of solutions offered, I submit to you that if you describe in some detail what you are trying to accomplish with your turntable, you will give the talented folks in this group a clearer picture of your problem and they will come up with workable ideas and maybe even the answer to your 'prayers.'
Jack
--

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I want to spin a heavy turntable 24" across. I want it to spin easily and for as long as possible while supporting about 100 pounds.
Replace the wheel and tire on a utility trailer, or a car or truck with a heavy table the same size as the tire turn it on edge so it is horizontal and give it the ability to sit in or on a work bench and it would work great.
I can get the hub, and the bearing. But getting the part the bearing sits in and fastening that to a work bench is beyond my ability and rather costly. I was hoping there was a product out there that would do this. I can find all kinds of shafts and bearings to spin a vertical disk like grinding stones but nothing that will support a horizontal disk.
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On a lazy susan I made, there were two pieces -- the revolving "plate", and the stand on which the plate sat. I mounted a large dowel to the back of the revolving plate, and then recessed the bearings from the front wheel of a bicycle into the stand., with a similar bearing set at the bottom of the column into which the dowel sat, This gave a very smooth and sturdy support to the plate, which turned easily with the touch of the hand.

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I thought of a bicycle wheel but I don't think it's strong enough. I thought a front tire off a motorcycle might be great using the disk brake as a flange to fasten the table. But I've never even seen a motorcycle wheel up close. I then to shy away from the greasy end of things, like cars and stuff.

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snipped-for-privacy@address.invalid wrote:

Do you want to do this because spinning a heavy turntable 24" across supporting 100 pounds gives you a woody, or is there some higher purpose to it? In other words is spinning the turntable your ultimate goal or is the turntable a means to an end? If it's a means to an end perhaps if you described that end you might get more useful advice.

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On Sun, 10 Apr 2005 23:28:01 -0400, "J. Clarke"

I want to be able to spin 100 pounds items on a 24" wide turntable that will spin freely as long as possible.
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snipped-for-privacy@address.invalid wrote:

No, knowing what you plan to use it for helps me figure out what would be a suitable design. And designing things _does_ give me a woody.
If you went to an engineer and asked for an estimate on the cost to design such a thing, whatever he came up with would be at least doubled due to "lack of definition".

Are these items symmetric or asymmetric? Balanced or unbalanced? How many RPM do you want? Is most of the mass distributed in the center, around the rim, uniformly, or what? Will there be any lateral force applied to the object, if so how much lateral force? How long do you need to spin the object? Is there an objection to powering it this device? Is there any possibility that the object being spun will shift during operation? Have you given any thought to retention? Are you going to be performing cutting operations of any kind on the device being spun? Painting? Anything else? What's your budget for this? What do you have already that might be reused?
Is there a college near you? If so visit the library and find a book on machine design and read it through. Then perhaps you'll understand why you're being asked for more definition.
--
--John
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J. Clarke wrote:

Very well put.
I grew to hate high tech and engineering because of sloppy problem definitions.
Nice/bad to see it wasn't only high tech that suffered from these problems.
Usually after I was awarded a job I would talk to the customer and say something along the lines of "OK now -- lets nail down all the specifics..." Then I would be told -- "you're the expert -- figure out what we want -- we don't have any more time to put into this". Then ..."Let us know when you have it working -- then we'll test it and tell you if we like it". Then "If it isn't up to standard you can fix it at your own cost cause you should'a been able to figure it out...".
Not all at once mind you -- just in dribs and drabs as it was revealed to you the pickle you'd got yourself into.
ROTFLMAO
--
Will
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WillR wrote:

Then there are the companies that have learned the hard way about lack of definition and overreact. I remember one fairly small job we did for Boeing (you could hold the part in one hand and it was all fabric) where we had to hire a guy to keep track of the spec revisions and clear out an office to hold it all--this was in the days before electronic distribution--the spec arrived on a pallet.

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J. Clarke wrote:

Pretty funny actually. I have seen that too. Since I won't do gov't contracts anymore I don't see it very much. I did enjoy your story tho... LOL
Been in High Tech since 68 -- have never worked for a company that wasn't all electronic format (of some kind) on the specs and product definitions -- except clients. So I can't really relate personally -- but it's still funny.
--
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On Mon, 11 Apr 2005 07:00:18 -0400, "J. Clarke"

Yes.
As many as humanly possible.

Both.
As much as you could apply with a stiff paint brush or rubber spatula.

Until I'm finished. The fewer times I have to spin it up the better.

Cost. I need this to spin 10-20 minutes once a day 4 days a week.

No.
As I have stated, a wheel hub assembly off a motor vehicle or utility trailer would probably be perfect. Getting a suitable one has proven to be a problem. Not being a welder it's also expensive. I didn't expect or ask anyone to design anything. I was hoping there might be a bearing assembly 'off the shelf' that might do this. Like bearing assemblies for making your own grinders and sanding machines only one that supports a horizontal disk. If the product doesn't exist I'm back to finding a suitable wheel and hub off a motor vehicle.
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snipped-for-privacy@address.invalid wrote:

So one should assume that the 100 pounds will be a point mass at 12 inches from the center?

Since you don't say anything about a retention I'm assuming that you are simply going to lay this point mass on the rim of your platform and allow friction to hold it. If that is not a valid assumption then please describe the retention.
To a first approximation and in the absence of any information about the mating material, the coefficient of friction of of any wood, according to the Wood Handbook, may be assumed to be .3 as a lower bound. That means that a 30 pound force will move your 100 pound mass off the table. Using a safety factor of 1.5, which is a very low safety factor typical of aircraft design, and if I've run my numbers properly that translates to about 24 RPM. Is that fast enough? If not then there is no point going on with this until you provide either a number or more definition.

Then again one must assume a point mass at the rim and the above analysis applies.

If the rubber spatula that I just broke is a fair sample that's about 5 pounds.

And how long will that be?

Why didn't you just say that you needed it to spin 10-20 minutes in the first place? Is that so difficult?

Well, actually you did whether you realize it or not.

There probably is. Have you looked in the McMaster and Grainger catalogs? But with the information you've given it's difficult to tell which particular components would do the job for you.

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--John
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On Mon, 11 Apr 2005 15:35:24 -0400, "J. Clarke"

The hundred pounds could be any size or shape, but I would only be spinning cylindrical items of course. I don't make anything over 100 pounds in one piece. I suspect my hub rated at 3600 pounds should be up to the job.:)
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