Hi there! I'm very new here and would like to get some suggestions about choosing a motor.
It is for an art installation I'm working on. Below you can see a sketch, which hopefully will help to explain the outcome I have in mind.
I'm looking for a motor that can generate a slow and smooth movement, and be able to drive an object around 0.5kg that's attached from the ceiling. I think the ideal speed will be between 1-3 mins for a full circle, also preferably as quiet as possible.
I've done some research but have seen many different suggestions such as (micro-step) stepper motor / closed loop system with encoder and Brushless DC motor etc. I'm wondering if anyone can help me choose the one that will work best for this. Thank you in advance for any input!
Probably simplest is a stepper motor microstepped. With 16x microstepping, you'd be at 17 steps/second which is very slow. It would be interesting to see how that works out.
If I'm bored enough this afternoon, I might just try it
I would recommend a gearmotor with a very high gear ratio, as they are very easy to control. Pololu sells 1000:1 motors, for example, which will run on as little as 1V and turn at around 1 RPM.
All of the weight of your project should be supported by a thrust bearing, which allows the motor output shaft to directly rotate the piece, without a load on the motor bearings.
Thanks for the reply! 17 steps/second sounds like a pretty smooth movement. I'm wondering what parameter of this kind of motor determines how heavy an object it can drive?
Hahaha, stepper motor seems to be a very popular choice for this kind of request. But I'm super interested to know why you think it wouldn't be the best option?
I think the agricultural tractor is an amazing invention, superb engineering and technology.
Would I recommend taking your kids to school in one? Or entering one in the Le Mans 24hour? Errrr, No.
The stepper motor was invented for command-and-control routers, 3-D printers, ink-jet printers, hard disk drives... Relatively speaking, it's an expensive, complex, inefficient, low-torque motor. But it has one ace up it's sleeve that no other type of motor can match - precise, repeatable positioning.
When they were introduced, stepper motors were heavy, expensive, required even more expensive control electronics and were relegated to applications only where precise positioning was required and you didn't have the need/budget for a servomotor.
These days stepper motors are cheap and ubiquitous. The control electronics are even more complex, but cost far, far less than before while providing a huge amount of flexibility. You can use them for a wide variety of applications as long as power efficiency isn't an issue.
Yeah, I used to turn up my nose at hobbyists using steppers as traction motors for mobile robots. But they're on to something: you can find them anywhere and with all the laser cutters and 3D printers, the controls cost almost nothing these days and they give you a lot more controllability (read: ease of changing your mind) at a low price point than pretty much anything else.
A 28byj stepper running at half steps has around 4096 steps per revolution and will run very slowly and not look "steppy". They are small, very inexpensive and use little power. I suggest the MobaTools library for steppers to get the half step functionality. Combined with a thrust bearing to support the load it should turn 0.5kg with ease.
I don't see anything in your project description that indicates you need any kind of computer control unless you wanted to vary the rotational speed. @jremington's suggestion of a gear motor or just a good old fashioned synchronous motor like used in clock/timers is available in many speeds. @Wawa's suggestion of a "mirror ball motor" is similar and might make installation easier.
Good point! Thanks for pointing this out and the summary.
Actually the for the original concept I would like to control the rotation speed with external data but that part needs to be developed further more conceptually. Thus I decide to skip it in the description just to simplify things a bit.
And due to the time pressure I might go with a synchronous motor for this stage, and build a computer controllable version for learning purpose on my side. We will see:)
Your art installation sounds interesting. When that time comes, a stepper motor approach might be the best. A gear motor would probably have to be further reduced in speed via a pulley/belt arrangement and would need to be speed controllable over a pretty wide range.
To solve the thrust bearing issue, a pulley/belt arrangement may simplify the design as well if using a stepper.
When doing projects analogous to yours, I get ideas from this website:
