Need ideas about using bearings for a spinning device

[georgiadoodle]

Hi!

I am a teacher and I want to make a few of these gadgets for a project this fall. I'd like to make zoetrope/phenakistoscope boxes. My students will ma ke the actual drawings, but I want to make some interactive display cases s o they can show their work off to the rest of the school.

I'm not sure how to explain what I need - sort of like a lazy susan on a ki tchen table, but that will spin for longer when spun by hand. I'd like kids to be able to run their hand around the outside rim of the wooden circular platform to get it spinning the right speed, then be able to just watch fo r maybe ten seconds without having to continue spinning it with their hand.

Ooh! Now I'm thinking of a roulette wheel. Those spin for a long time. I've also thought of skateboard and fidget spinner bearings, but not really sur e what would be my best choice to make this work well and be cost-effective .

Extra, probably unnecessary info: I plan on encasing each one in a plexigla ss upper casing with just the edge of the spinning platform sticking out on e side so the kids can spin it. This would all be much easier if I could ju st trust middle school students not to destroy things! :)

Thanks for any thoughts! Lori

[hubops]

Lazy-susan bearings are available -

not sure how long they would spin ?

Roller blade wheels :

Bicycle wheel axle & bearings - from a discarded bent wheel ?

John T.

[J. Clarke]

My goto would be skateboard bearings. Readily available and cheap.

[whit3rd]

To both bear weight and spin, a lazy-susan bearing is not really going to spin nicely (they're intended not to fling the condiments around, there's a lot of friction in the design).

A phonograph turntable, or a sits-on-a-spiindle cup/point bearing, might be suitable though. At the high end, an automobile wheel bearing (tapered roller bearing) can take lots of load (assuming you can machine a mount to hold it...).

[georgiadoodle]

I have a couple of 20" bikes sitting around - I'll try the wheels and see if that works, thanks! :)

Lori

[Mark H]

Old record player ?

[ads]

The 4" bearing supports up to 300lbs and a disk of 12" to 25". That should work nicely when loaded lightly and should also resist any mis-directed attention.

[pyotr filipivich]

[e-mail] on Fri, 3 Jul 2020 09:53:42 -0700 (PDT) typed in rec.woodworking the following:

Lazy susans mostly have a track and spheres which will bear the weight and roll. (That's why 8th grade shop classes make lazy susans using marbles for bearing. "Cheap" but works)

What you want are "regular" bearings: bicycle wheels would serve, support the axle. Details as an exercise for the student. After that its just about anything with an axle and a set of bearings. Replacement bearings can be had at hardware stores, part shops, skate board, or biycle shops.

Research how roulette wheels are mounted. Could be they pivot on a post. (They've existed for centuries.)

The Plexiglas could also serve as the upper mount for an axle.

[krw]

Bicycle wheels may not be the best choice. They're intended to take a force orthogonal to the axle. You're asking it to take a parallel force. One bearing is going to take the load and the other nothing. The force is also at the edges of the race. Not ideal, to say the least.

[georgiadoodle]

There can't be any axle above the rotating platform, because you have to be able to look from one side to the other, right through the center.

Would it matter if there really won't be much weight on it, other than the wheel itself (I wouldn't even keep the tire)? I can use really lightweight materials for the platform and the cylinder that sits on top.

[hubops]

It would need to be a big load over a big period of time to affect a bicycle axle & bearings ... I doubt this school project will wear out the bearing race .. I suspect that the teacher is looking for something cheap < free > and readily available ; and functional. ie: old bicycle wheels John T.

[J. Clarke]

I just had an idea. You want it to spin for 10 seconds you say? Just hang it from a piece of string. The string will wind up when you give a spin but if you size everything right it should spin for 10 seconds without any difficulty. Or you can pre-wind the string and let gravity power it as the string unwinds.

[krw]

No, it wouldn't. Over time, the grease will be useless. That's NOT they way they were intended to be used. It's like a drill press being used for sanding. Not good.

[krw]

Weight is your friend. The more weight the more rotational energy stored. The energy used (friction) is nearly the same, at the same RPM.

[krw]

I think the record player is the best idea yet. What you want is a needle point bearing, like a fidget spinner/dreidel/stromvos. The center point should be as sharp and as hard as possible.

[Markem]

Belt driven turntable yes (dump the belt), direct drive turntable would not be my choice.

[Joe Gwinn]

The right way to do such a thing with real bearings is to use a short vertical shaft with two bearings, the upper one having tapered rollers, the botton having needle rollers. The load is on a circular plate attached perpendicular to the vertical shaft. The vertical load is carried by the upper bearing, and the bottom bearing resists the tipover forces. The reason for needle rollers is to not trap the shaft axially between bearings - there needs to be some give, especially over temperature.

If the frame will be made of wood, one will need to desgn for tolerance of angular misalignment, but there is enough give that axial trapping will not be a problem.

One source of suitable bearings:

Self-aligning flanged bearings:

Joe Gwinn

[J. Clarke]

GAWD. Talk about overkill.

This is a zoetrope

This is a phenakistoscope

[Clare Snyder]

Finf an old hard drive, floppy drive, or CD Rom drive and fasten the platform to the disk or motor - use the bearings of the drive - the motor just goes along for the ride.

[Bob La Londe]

Spin duration may be improved by mass. It takes more energy to accelerate more mass, but it also takes longer for parasitic loads to reduce velocity. This is only true up to a point. There will be a mass threshold that will overcome the friction reduction of the bearings. Balance is also an issue. If the load is well balanced the bearing will work better up to its limits.