Gear Driven Mobile With LEDs & Arduino

Introduction

We had an assignment at school about happy hacking, which in short meant we had to design something for a problem that would make the situation better. Something that bothers us at school is the fact that the building seems to be made to get lost in, but nobody ever really goes to explore the building. So we figured we would make something awesome, hide it somewhere in school and show a live image of it in the school cafeteria. That way people would get interested and (hopefully) start looking for the product, while they unconsciously explore the building. We wanted to make something that turned and had a fantasy kind of vibe, so we chose to make multiple gears with planets hanging from them. It sort of has a double purpose, because you can also take a moment for yourself and (in a way of speaking) be the middle of the universe. But of course you can hang anything you want from the gears, as long as it doesn't affect the way it spins.

Step 1: Parts List

1- 4 mm mdf (for gears)

2- 2 cm multiplex (base plate) Must fit all the gears, in the order you want them to be

3- 2 cm long screws (about 4 mm thick)

4- Metal tube (the screws must fit inside, but must be able to spin)

5- Dc motor (we used one from an electric kids car)

6- Power supply (voltage must be adjustable)

7- Plastic sheets useable for vacuum forming & orbs to use as a base

8- 3 mm wire

9- Paint

10- Spray varnish

11- Arduino

12- LED lights, we used 12, but you can use as many as you like

13- Wires

14- Resistors, make sure that they are compatible with your LED’s

15- Breadboard

Step 2: The Mechanics Behind the Gears and Lights

We didn’t design the gears ourselves but used a handy website so we could see how the gears would turn and decide how we wanted our final product to look from that. You can find it here. ( http://geargenerator.com/ ) Or just take our gears.(insert dxf file for gears)

For the lights we didn’t know yet how we wanted to set them up exactly except that we wanted a lot of LED’s. We decided to try this instructable to control a lot of lights. https://www.instructables.com/id/Controlling-20-Le... In the end this didn’t work out because the coding was too convoluted to do on a short notice (for some novices at least) and we ended up not needing all that many leds. If you do however need a solution to control many leds do check it out.

This is the wiring setup we eventually went with:

Notice that the pins we connected the LED’s to are all pwm enabled so we
could do some fancy fading stuff. Find out how to fade your LED’s here https://www.arduino.cc/en/Tutorial/Fading

Step 3: Construction & Wiring

Lasercut the gears linked above on the 4 mm mdf and space them however you like on the multiplex.

Step 4:

-Cut 4 mm pieces of metal tube and make holes in the middle of the mdf, the same width as the diameter of the metal tube, preferably just a little bit smaller to make a snug fit. Put the pieces of tube inside the gears and make sure they are secured tightly. We did this because we were going to secure the gears with screws, and we didn’t want the screws wearing out the holes.

- Make small discs of mdf with a width of approximately 4 cm and with a hole in the middle using the same drillbit you used for the metal tube. Put one disc on the back of each gear, but don't glue or secure it otherwise, they must be able to spin later on. You reduce friction this way, and therefore stress on your motor as well.

Step 5:

- Place the gears on the multiplex again and make sure they are in the right order, and that they are all touching another gear. Secure them with the screws, but don't secure the biggest one yet, because this is the one we will be securing our motor to. Also make sure the gears are secured well, but can still spin nicely.

Step 6:

- Secure your motor. In our case this meant we had to cut a hole in the middle of the biggest gear, so it would fit around the motor. And because it had to be the same height as the other gears we put a disc of mdf behind it with a hole in the middle with the same shape as the connection point on the motor. Looking back it probably would have been best if we had laser cut this piece as well (also in the middle of the biggest gear), luckily it all worked out in the end.

Step 7:

- Put the biggest gear in the right place and make a hole in the middle of the multiplex so your motor can fit through, but still has a way of getting secured on the back of the board.

- In order of steps we did the following to secure the motor: glue the mdf disc perfectly in the middle of the biggest gear and let it dry. Put the gear in the right place en put the motor from the back of the plate in the right place. We used a piece of wood with some 3 mm metal thread through the hole in the middle of our motor connection piece and bend the thread to make sure the gears wouldn't fall off when the board is turned upside down.

Step 8: Vacuum Forming

- Vacuum forming
We used vacuum forming to multiply the amount of orbs we had for the planets. We got the orbs at our local crafts store. If you don’t have a vacuum former available you can just buy all your materials at once instead and skip this step.

Step 9: Painting

- You can use whatever paint suits you, we used gouache and brushes to get some nice dry brush effects, but you could also use an airbrush or spray paint. Make sure that whatever paint you put there lets light shine through for the best effect.

Step 10: Arduino/ Power Supply for Motor

-With everything set up we are finally ready to wire up the arduino and do some coding. To get the LED’s inside of the planets we soldered some longer wire to the LED’s. For the code we just put something simple together. You can download my code here. We started by deciding what kind of lighting effects we wanted. For every effect we wrote a function we could call on in whatever order we liked. This way you can easily create interesting looking stuff without too much repeating code.

We decided we didn’t want to control the motor with the arduino, although it is also possible to do that. We didn’t want to accidentally fry our board by overvolting it, so we went with a seperate power supply. With this power supply we were able to control the output and make the motor spin at just the speed we needed. In hindsight we totally could have controlled it with the arduino, but we didn’t know beforehand that the motor had a built in safety and didn’t draw as much power.

Step 11: Testing Each Component Separately

Before putting everything together make sure every component works. If something doesn’t work now it is still relatively easy to fix.

Step 12: Final Product!

Here are some videos of what our project looked like. There is definitely room for improvement, but we got our idea across. Next time we would take more time to fine tune everything, and take more time assembling.

Thanks for reading!