# Electrical Need help for DIY art project

#### TwelweTwo

Hello! I am an aspiring artist and have a terrible expertise in tech, but I have this idea in mind and strong desire to make it come to life, so I was hoping I could get some help here.

The idea is to create a moving sculpture which is going to refer to the sun. What you see in the sketch 2 as a circle is basically a lamp and I want to make make it move across the room. The movement that I want to make is primitively represented in the first sketch. I want it to move in circle on the plane parallel to the ceiling and up and down vertically (simultaneously).

I figured that I will need 2 moving elements, so first obviously the motor to make the circular movement. For the vertical movement I want to attach the lamp to the thread and have a mechanism to pull/release it. I also need to synchronise those two movements. More specifically I need to know what kind of motors I need to look for and how to connect them and what to use a central hub to orchestrate the movement ( I am thinking Arduino?).

As for the weight of the lamp I am not quite sure yet, as I don't have a prototype yet and the size of the whole construction will depend on the room that will be available to me, but I am estimating max. 10kg.

As I said I have very little knowledge in the technical aspect necessary for the execution and I don't really know where to start, I would very much appreciate if you guys can give me some practical advices or point me in the right direction for research.

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#### mfb

Mentor
How quickly is it supposed to move up/down? One cycle per revolution (making the overall motion a tilted ellipse)? Much slower? Faster? If the motion is synchronized it might be possible to make both with a single motor.

Some other numbers would be useful as well.

#### TwelweTwo

First of all, thanks for reply!

How quickly is it supposed to move up/down? One cycle per revolution (making the overall motion a tilted ellipse)?
Precisely that. The movement should give a tilted ellipse as a result. I am imagining one cycle should take around 30min, but I am considering coming up with a more interesting number related to cosmological constant for example. Using one motor will make my life much easier I imagine, but I was not sure how that can be achieved.

The whole construction will be attached to the ceiling. As for the numbers I am not sure what exactly you mean? If you mean the size wise, I cannot say that for sure, but I think radius of the circle will be from 2 to 3 meters and the lamp should be 1 meter in the diameter.

#### berkeman

Mentor
The idea is to create a moving sculpture which is going to refer to the sun.
What does that mean? Are you going to have a stationary lamp globe in the center, and your oribiting object will be like a planet? Or is the moving object going to be lit up? If the latter, what is it supposed to be orbiting? A Black Hole maybe?

In any case, to have it rotate on a tilted axis, you can tilt the main rotor shaft. To get it to move in and out in an ellipse shape, you can change the arm length from the shaft to the object as a function of the angle around the arc. To get a nice ellipse, it may be necessary to use a different motor for the arm length changes. Maybe use a simple geared-down motor that is synchronous with the 50Hz/60Hz AC Mains power frequency (geared down to your low rotation rate like a clock), and use a stepper motor to linearly actuate the radius arm to give you an ellipse. That is pretty easy to do with an Arduino microcontroller, for example.

#### anorlunda

Mentor
Gold Member
Can you pay an artist's sketch of your concept?

#### TwelweTwo

What does that mean? Are you going to have a stationary lamp globe in the center, and your oribiting object will be like a planet? Or is the moving object going to be lit up? If the latter, what is it supposed to be orbiting? A Black Hole maybe?

In any case, to have it rotate on a tilted axis, you can tilt the main rotor shaft. To get it to move in and out in an ellipse shape, you can change the arm length from the shaft to the object as a function of the angle around the arc. To get a nice ellipse, it may be necessary to use a different motor for the arm length changes. Maybe use a simple geared-down motor that is synchronous with the 50Hz/60Hz AC Mains power frequency (geared down to your low rotation rate like a clock), and use a stepper motor to linearly actuate the radius arm to give you an ellipse. That is pretty easy to do with an Arduino microcontroller, for example.
The moving part will be the sun which is going to be lit up, I was thinking that it will orbit the galaxy which is going to be suggested by the object on the floor possibly similar to the one in the photo. But it is not established yet and to be honest I love the blackhole idea!

Thanks for the suggestion I will look into the method you described.

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#### TwelweTwo

Can you pay an artist's sketch of your concept?
Sorry I don't understand what you mean?

#### anorlunda

Mentor
Gold Member
Sorry, auto spell.

Call
Can you pay an artist's sketch of your concept?
Sorry.

Can you post an artist's sketch.

#### TwelweTwo

Sorry, auto spell.

Call

Sorry.

Can you post an artist's sketch.
Here is something I sketched out, I hope it won't make things more confusing, hehe. It basically shows two extremum points of the movement the way I have initially thought about this.

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#### Spinnor

Gold Member

If the end of the rope that is fixed at the wall is far enough away from the rotating arm then the motion of the sphere is nearly elliptical with the plane of the ellipse tilted at a 45 degree angle from the floor?

#### mfb

Mentor
@Spinnor: That's what I was thinking about.

It doesn't have to be a wall, mounting something to the ceiling works as well as long as it is outside the area the rotating arm covers and ends lower than that arm.

#### Spinnor

Gold Member
This might do the trick,

All you need is a cheap raspberry pi computer + raspberry pi motor controller + geared stepper motors + friend who knows a thing or two about robotics + a machine shop + ?.

#### TwelweTwo

Thanks for the replies guys, I will try it with the method you suggested, however I will only have the opportunity to work on it full-scale in September. For fun here is the link to a quick prototype I made today from the sketch of Spinnor https://we.tl/t-fru9vbzPRp .
I think I like the elegance and straight-forwardness of this method but I am a bit afraid that the rope will become too prevailing element of sculpture, but that will only be clear once I make a first full size try out.

#### TwelweTwo

This might do the trick,

View attachment 247714

All you need is a cheap raspberry pi computer + raspberry pi motor controller + geared stepper motors + friend who knows a thing or two about robotics + a machine shop + ?.

That sounds very doable and exciting!

#### Spinnor

Gold Member
You could use the right size fishing line, very strong and thin. You also might use a small pulley to reduce friction for the fishing line.

#### JBA

Gold Member
With regard to the ellipse, if using the post #10 method with a cord, an ellipse major chord length twice that of the ellipse minor chord based upon the diameter of the rotating arm can be created by using a single sheave pulley at the wall and a double sheave swiveled pulley on the arm with the end of the cord connected to the wall/ceiling location of the single pulley.
Additionally, by using a transparent fishing line, as suggested above, and painting the arm and its pulley assembly to match the room ceiling color and a similarly colored cover with a side opening for the wall or ceiling mounted pulley assembly you might minimize the distraction by those elements, at least for non-STEM viewers who are going to immediately start investigating how you achieved your ellipse motion anyway.

#### TwelweTwo

With regard to the ellipse, if using the post #10 method with a cord, an ellipse major chord length twice that of the ellipse minor chord based upon the diameter of the rotating arm can be created by using a single sheave pulley at the wall and a double sheave swiveled pulley on the arm with the end of the cord connected to the wall/ceiling location of the single pulley.
Additionally, by using a transparent fishing line, as suggested above, and painting the arm and its pulley assembly to match the room ceiling color and a similarly colored cover with a side opening for the wall or ceiling mounted pulley assembly you might minimize the distraction by those elements, at least for non-STEM viewers who are going to immediately start investigating how you achieved your ellipse motion anyway.
Thanks for the in depth answer!

"Need help for DIY art project"

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