This is partially an idea, but really more a request for your ideas too.
I know a car turntable is not a new idea: you can buy them I think for around $30,000.
I need one, and am trying to figure out how to make a home-made one. My basic idea is a round platform, and underneath it on the outside there is a trough with a nice flat concrete floor, where the wheels will roll as it turns. To divide the problem into different areas:
The platform - what should it be made of? It has to have interlock put on top to blend it with the rest of the driveway. A steel circle custom-fabricated? Steel reinforced concrete?
The rolling method - have the platform roll on wheels that are attached to the floor, or have the wheels on the platform? What kind of wheels, layout etc.
As it rolls, there have to probably be other wheels mouted horizontally, both facing in and out, to stop the thing from rolling in an unbalbnced fashion and jamming.
The turning energy problem - have the whole platform geared on the outside edge? Seems a bit hard. Or have a rubber wheel pressing against the side of the platform (underneath, hidden from view of course) and rely on friction to transfer the power to the platform?
Power source - I presume some kind of electric motor geared down with a series of pulleys. It could all be housed in a small pit adjacent to the turntable, with a steel or other hatch cover.
control - turning amount - we of course need a 180 degree turn. Should i use some kind of apparatus which is turned on and off by a switch trigger mounted on the wheel? Or maybe I can time how long it takes to turn, then have a timer mechanism?
Remote control: I need to use remote control from in the car to do this, and I haven't a clue how they work and how to hook it up with the motor.
Maintenance: I have alot of leaves, I dont want the whole thing gummed up with gunk. In addition, I can't make the platform so heavy that, once in place, I can never get in to service the wheels etc.
Any and all help appreciated.-- marquisdenet, Jul 02 2009 car turntable http://www.hovair.c.../car-turntables.htmcar turntable [marquisdenet, Jul 03 2009] Something a bit different: car, no turntable needed http://www.youtube....watch?v=0uYsjs_xlegWho saw this one already?? [kindachewy, Jul 08 2009] You could put a small ice rink in front of the garage. and use a circular linear motor underneath to magnetically spin the car around.
Really though... If you're in a non-freezing zone I imagine you could teflon pads instead of wheels (would have to be replaced occasionally.
A ring would be superior to a complete platform in some respects.
I don't see any way of making one cheap but what are the rest of the parameters ? (weather, driveway length, yard size, garage?). Could you make do with a semicircular driveway with an entrance and exit?-- FlyingToaster, Jul 02 2009 The basis for this could be a basic towable twin axle car trailer.
Choose one with a sturdy steel frame.
Weld a pivot at the centre of gravity, underneath, between the axles.
Fabricate a couple of brackets to attach to each end to carry heavy duty castors.
Weld a pin on top of a heavy duty motorcycle jack. Bolt it to the floor where the turntable is going to pivot.
Drive car onto trailer and centre it over the pivot (paint marks to aid this, or fix bump stops for the front wheels). Jack up the centre point to lift the trailer roadwheels just clear of the ground. Drop the stabilising castors. Swing the turntable.
Remote, powered operation is going to be seriously difficult - better to buy a premade unit.-- 8th of 7, Jul 02 2009 //Remote powered operation// if there's sufficient drainage and weatherproofing, a garage door opener could sit underneath the platform and turn the hub.-- FlyingToaster, Jul 02 2009 Like [8th]'s - particularly as you can quite easily remove the whole thing somewhere else when you don't want it in the way, or - importanty - move house, etc. (want to bun the anno!)
As for power (won't work with the trailer, but could with a solid platform). Build a rolling-road into the platform at front or rear depending on car configuration, or both to cover the options.
Drive car on ... then allow the car's engine to drive the ro-road, which then turns various gears and connecting parts to move the platform
Then test out the robustness of the system by tying the car down tight and seeing how fast you can make it spin-- kindachewy, Jul 02 2009 Float it. Circular pond, circular floaty thing (lots of polystyrene boxes and some imagination). You could turn it by hand - no motor needed.-- MaxwellBuchanan, Jul 02 2009 Use a mercury pool. Some lighthouses used mercury to act as a "frictionless" bearing for the lens assembly. It's so dense, it doesn't need to be vey deep.-- 8th of 7, Jul 02 2009 I think the average householder will have problems in purchasing large amounts of mercury.-- MaxwellBuchanan, Jul 02 2009 Make a shallow decorative fountain, 10 min before you get home call and punch in a code that starts up the freezing tubes embedded underneath so by the time you get there you can just park on the ice. Turn by hand.
Concrete trench, bowling balls, used Stargate: MacGyver would be proud.-- FlyingToaster, Jul 02 2009 For all season applications, you could park the car on a large flat disc which rests on thousands of air jets.
I envision something with large rough wooden spools turned by thick chains, suspended boulder counterweights, and crews of sweating slaves; perhaps an ogre if you can find one.-- tatterdemalion, Jul 03 2009 Just out of interest, why do you need a car turntable?-- hippo, Jul 03 2009 I'm sure you're familiar with junkyards for cars? Well, such things also exist for heavy equipment.
Find one in the phone book, and go see what you can dig up. Anything from a heavy truck wheel or clutch bearing to a backhoe or crane house pivot...
I think I would start looking for a rear end from a tractor. Particularly if I could get one with wheels, because a tractor wheel would be a huge head start on building the platform. Chop off one end of the housing, weld it down to something as the base; it has the bearing in the end. The axle inside is available for drive options, if you want. Or drive the wheel from the outside edge. Scavenge gears and whatnot from the differential. Keep the brake intact, it'll be very useful.
Wrap a cable around the outer part of your table. Then through pulleys up to a weight suspended high enough that its distance to the ground is half the circumference of the part of the table the cable goes around. Then to a pulley on the ground below the weight, then back to and around the table again.
Drive onto the table. Release the brakes. (Actually, use the brake to keep the table under control.) When the weight gets to the ground, your car is facing in the roll-off direction.
After driving off the table, you can use a rope that goes half-way round the table and then attaches to your vehicle to turn the table back to its start position, hoisting the weight for next use.-- lurch, Jul 03 2009 //I think the average householder will have problems in purchasing large amounts of mercury//Just keep buying cans of tuna or energy-saving light bulbs.-- coprocephalous, Jul 03 2009 hippo - the reason I want it is twofold: to save space in my backyard area, which now has to be reserved for turning the cars around, and to stop me from having to back down a long narrow alley (my driveway) and onto a busy road.
Besides, it would be cool!
8th - I think the centre pivot is a great idea, never thought of that. But I don't quite get the trailer idea - if the thing is pivoting about it's centre, doesn't that inmply that the rear (fixed) axle would be dragged sideways?
But I do like the ide of an axle, pivoting about its centre, as the basis for it. Completely solves the problem of needing additionally horizontally mounted wheels. But I think we would need two axles, and I guess in order to handle the problem of where they cross in the centre, one would have to be higher than the other, with correspondingly larger diameter wheels so that they both equally take the weight.
In addition, because the axles themselves would be different heights, there would need to be some kind of spacers to maintain equal contact with the platform itself.-- marquisdenet, Jul 03 2009 How about this: Build a steel frame, large enough to fit a turntable within. From the top-middle of the steel frame hangs a single steel cable. From this cable hangs a rectangular cage with a floor. It hangs in a shallow pit so that the floor of the cage is level with the ground. The uprights of this cage can be securely clipped to the uprights of the main steel frame. To operate, drive your car into the cage and put the handbrake on. Unclip the cage from the supporting frame and rotate the cage by hand and reclip it when it's facing the opposite direction.-- hippo, Jul 03 2009 It needs to be an outside turntable, not an inside one.-- marquisdenet, Jul 03 2009 Well sure, back in the '80s when The Cars rocked pretty hard, it must have cost a lot to make a record player that would only play their music. Are you saying someone manufactured turntables based on the self-breaking record player concept described in "Godel, Escher, Bach" by Douglas Hofstadter?
My .02c: I like [FT's] idea of Teflon under the wheels... you might make wheeled ramps to drive up on.
You might try building a big thrust bearing. Get a bunch of hard plastic balls for the bearings. Use plywood to make a huge bearing race and upper and lower surfaces. Epoxy sheets together and paint with epoxy paint. Stick a big metal stake through the center of all the plywood as a pivot. My wild guess at costs for this approach is ~$500 for parts (plywood, balls, glue, paint), five solid days of designing, buying, cutting, gluing, painting, etc., and a 50% chance of it being unusable.-- sninctown, Jul 03 2009 The "ball pool" idea is simple and has many advantages.
A large number of small, smooth, incompressible spheres would give quite a good bearing surface. Golf balls would be too rough, and probably too small. Solid plastic spheres, about 75mm in diameter, would be the best. Metal would corrode, and be heavy and expensive; ceramic might crack under load.
Since the load would be distributed over a wide area, it might be possible to make the upper and lower bearing faces out of shuttering ply; one sheet for the lower bearing, resting on a hard surface i.e. in a concrete pit, and two layers, cross-laid and painted, for the upper surface.-- 8th of 7, Jul 04 2009 If you printed an LP on the car roof, and added a pick up arm, with stylus, you could use your car collection as playable albums. Ford Mustwang anyone?-- xenzag, Jul 04 2009 I built a turntable for my long skinny driveway. But instead of trying to reinvent the wheel, I purchased all the components from a company that actually builds the things everyday! They had all the components that we needed. Was all new stuff, just an obsolete model that was apparently still in their inventory. They install residential turntables all over the country for $22,000-$29,000, but we paid about $11,000 (+ shipping) for all the components. The weight was over 3,500 lbs, so we figured they must have spent much more than that on materials and labor alone. It all went together without a problem, was very well built, and will likely last much longer than me. Even included the motor and electronics to operate it. Not sure if you could still find a deal like that, but it’s worth looking into.-- Everett, Jul 06 2009 Concrete bearing race, billiard ball bearings, ply upper-- BunsenHoneydew, Jul 08 2009 You're overcomplicating things. You only ever need to turn 180' so an imbalanced flat disc is all you need, slightly raised on one side.
When no weight is present on the wheel, a weight under the disc at one point of the circumference causes the disc to be 'at rest' against a stopper. The stopper is at a fixed position on the ground, at the lower side of the disc.
The car drives on (and slightly uphill) onto the disc. Since the engine is the typically the heavier end of the car, having it raised higher than the rear of the car will naturally cause the disc to turn. Thus, from a fixed position on the disc, the weight at the front of the car turns until the stopper point is reached again.
When the car leaves, the disc will rotate 180' back to it's resting point, ready to rotate once again.
edit: if I had more time I'd fire up the Phun utility and take some screenshots or an animated GIF - it's a fun tool that's very useful for explaining this kind of brainstorming.-- gth, Jul 08 2009 [gth] tilt the whole mechanism, spindle included. That way it doesn't need to spin back when the car's off... you'd want a brake on it though so you could exit the car/mechanism, before letting it spin.-- FlyingToaster, Jul 09 2009 For a bit of fun, check the link ...-- kindachewy, Jul 09 2009 random, halfbakery