Motor expertise needed


#1

OK, bare with me here as I try and describe something in my head. I have a vision for a moving art piece that will range from maybe 18" to 2’-ish wide to hang on the wall. It involves pieces rotating around center piece. I would love at least two layers moving in opposite directions rotating around each other, but I’m willing to start simple if need be. I would be happy with a static center piece with outside piece(s) moving around it. In my total fantasy world, I would have multiple individual cutouts rotating around a center piece and the cutouts would also undulate up and down. The piece will be out of thin acrylic/wood or any combination of the two. So while it won’t be super heavy, it certainly will be heavier than a normal set clock hands.

Here’s my problem, motors and electrical things are way out of my realm. I have not a clue where to even begin to find a motor to suit my needs or what kind of mechanism one would need to achieve the movement. My mind can only envision a clock type mechanism, but I still can’t picture how it would work. I don’t even know what to search for and everything I’ve tried isn’t coming close. (For some reason “clock movement on steroids” yielded no results. Weird :slight_smile: ) Anyone know what technical terms I would use for such a beast or where one would find such a thing? I’m kinda at a complete loss on where to begin. Any suggestions at all would be welcome.


#2

I like where you are going with this, I’ve had similar thoughts. Search 'kinetic art".

As to the movement, do you want it to move at the speed of a clock or be a bit more energetic?

You can do most anything you want with one strong dc motor if you are willing to design the gears to run it. Oh, and they can be part of the art as well.

Another thought, Arduino, and servos. Do you program at all?


#3

You’re going to want (most likely) to look for gearmotors or synchronous gearmotors. Or, if you are willing to program, stepper motors or geared steppers. The cheapest geared steppers (lots of backlash in the gear train but otherwise fairly accurate) are about $5 a pop. On the other hand, synchronous gearmotors off AC are designed to run 24/7/forever…

(I’ve done hobby designs and builds of a lot of this kind of stuff.) There are also continuous rotation servos, which are basically motors with accurate speed/direction control, but they tend to cost more.


#4

I have seen people hack tiny servos so they just rotate when you apply power. They produce quite a nice light gearmotor.


#5

I wonder if you could use an actual clock motor, they seem to make ones that are designed for large clocks (the keyword seems to be “high torque”). It might work if your piece is balanced, my guess is these aren’t really designed to lift weights.

E.g. https://www.clockparts.com/isi-continuous-sweep-high-torque-movement/


#6

Are you set on electrical solutions? Seems it would be fairly straight forward to drive it with a weight and a pendulum to slow it down.

I think we had some clock/watch people on the forums who referred to the gears and drives of a clock as movements.


#7

I’m oversimplifying here, but I hope it will give you enough information to be successful in your search.

Probably the first thing to do is to decide how “fast” you want this thing to be. What I mean here is, how long you would expect it to take to complete one cycle. Motors are typically rated by their speed in Revolutions Per Minute (RPM)

Then you need to decide if you want this to plug into a wall outlet or to run on batteries. That will dictate whether you’re looking for an AC motor or a DC motor respectively.

The kinds of speeds we find in clock mechanisms are very slow for electric motors, and in order to achieve this they are geared down heavily. You may decide that visible reduction gears are a design element that you’d like to incorporate into your work, or maybe not. If you want to skip that bit, then you ought to look for a “gearmotor” which really is just a motor with a gear reduction. Typically this is done to increase torque (“strength”) or the output, but for your purposes, you want the slower speeds.

Now all of that having been said, I’m going to recommend that you find a discarded microwave oven and pull it apart to retrieve the turntable motor. These are typically rated for 120V A.C. at 6 RPM. You may be able to simply buy one as a replacement part for ten bucks or so.

I make that recommendation because it removes so much of the complexity for you:

  • You get a slow speed, out of the box (6 RPM).
  • You don’t have to worry about wiring up batteries.
  • They’re cheap and easy to get.

#8

I don’t see much challenge in making the combination motion. I would do it with an inner hidden shaped cam that the arms would travel against. The arms could rotate, the cam would be fixed, and the ring could also rotate. Rubber bands or springs would provide tension against the cam that would keep everything in place.
The most challenging part would be two speed rotational motion, though that can be solved with a gear design. Depending on the size, I am guessing it might take me about 5 hours to design.


#9

@kittski I think you might enjoy this book: