Rotational decorations hanging from the ceiling look awesome. They capture our interest and lead us to wonder how they work. In this instructable I describe how to build one of those, focusing on the mechanism and leaving the decoration part up to you (but still showing you two implementations).
My mother-in-law saw a ceiling decoration in a local Christmas store and fell immediately in love, but it was too expensive. She told my wife about it and my wife said: "Hey, perhaps Germán can do one for you." And that's how I ended up making this. In the end, it was a gift for my mother-in-law, and because she was really happy with the result, I also made one for my mother. Two Christmas gifts made in about two weekends, and everybody happy!
Step 1: Materials
- Arduino Uno
- AC/DC Adapter, output: 9V-1A
- Micro gearmotor 200 rpm, 1.8Kg/cm
- CD Spindle case (for 50 CDs)
- Balsa wood (square, 1cm per side)
- Metal axis (8cm long)
- 1 small eyebolt, 2 screws
- Plastic pulleys:
- 5cm diameter
- 1cm diameter
- 3.5cm diameter
- 2.5cm diameter
- 1.75cm diameter
3 in 1 oil (just a couple of drops)
Step 2: Solder the Circuit / Upload Code to Arduino Uno
The circuit was taken from the SparkFun Inventor's Kit (Circuit #12: Spinning a motor). You can find there the rationale behind it.
The couple of wires that go to the motor need to be about 28cm long.
Source code can be accessed at GitHub: https://github.com/gacarrillor/electronics/blob/m...
Upload the code to your Arduino Uno and continue to the next step.
Step 3: Pulleys and Axis
Since the gearmotor we got rotates relatively quick, we need to reduce its speed. To achieve that we use 2 pulleys; the 1cm diameter pulley rotates with the gearmotor and, through the rubber band, transfers rotation to the 5cm diameter pulley, which reduces the speed for its axis.
Start cutting the axis to make its length to match the CD spindle lid height; in our case 8.5cm long.
We need to attach the 1cm diameter pulley to the motor axis. For that, broaden the pulley hole until it fits into the motor axis. We broadened such hole by introducing screws that are progressively bigger, until we got the hole diameter we need. You might also need to gently use a hammer to finish introducing the pulley. Paste the pulley to the gearmotor axis with Super Bonder as we don't want it to be loose.
On the other hand, insert both the 5cm and 3.5cm diameter pulleys into the main axis, but don't paste these pulleys yet.
Step 4: Cut Center Spindle Piece Off the Base
We need to cut the center spindle piece off the base. For that we used an old hacksaw.
Fit the balsa wood horizontally and across the base center point. Make a little hole into the balsa wood and insert there around 1.5cm of the lollipop stick. Such stick hole will hold the main axis in a vertical position while still allowing it to rotate with low friction. Paste the balsa wood to the base with hot melt glue, but don't paste the lollipop stick to the balsa wood, as you may need to adjust it afterwards.
Step 5: Make a Hole in the CD Spindle Top Lid
The main axis needs to cross the CD spindle top lid. So, make a hole in the center that is just a bit wider than the axis, allowing it to rotate almost freely while still holding it in a vertical position. We made this hole by introducing screws that are progressively bigger, until we get the required diameter.
Step 6: Laser Cut Design and Wiring the Motor
We design some layers of MDF to hold the motor in a vertical position and leave enough space for both the main axis and the Arduino. Additionally, a small hole allows us to connect the motor to the circuit. You might need to put two pieces of a popsicle stick around the motor to make it more stable. If you do that, beware of obstructing the pulley attached to the motor.
Files with vectors are attached in PDF and SVG. You can observe that the files include a ring with holes. This ring will be used to hang the Christmas decoration. You can, of course, experiment with your own design.
Step 7: Fix First Two Pulleys to the Axis
Make sure maximum 1cm of the axis is out of the CD spindle top lid. The 3.5cm diameter pulley will be in contact with the CD spindle case interior. Level the 5cm diameter pulley with the pulley attached to the motor. Now you can paste both pulleys to the axis with Super Bonder.
Put some oil on the part of the CD spindle case that makes contact with the 3.5cm diameter pulley, in order to reduce friction between them.
Step 8: Fix the Other Two Pulleys to the Outside Part of the Axis
Insert the eyebolt into the 1.75cm diameter pulley. The eyebolt will hold the Christmas decoration.
Insert the 2.5cm diameter pulley to the outside part of the axis, but don't let the axis to cross beyond the pulley.
Paste both pulleys with good quantity of Super Bonder, including the eyebolt end and the axis end.
Step 9: Connect the Arduino to the Power Supply and to the Soldered Circuit
Make the following connections from the Arduino Uno to the soldered circuit:
- Pin 3 to the transistor base.
- Ground (GND) to the transistor emitter.
- 5V to the transistor collector.
You can observe the Fritzing diagram in step 2 to make sure you're connecting everything properly.
Finally, plug in the adapter to the Arduino Uno and open a little hole in the CD spindle case to let the adapter wire go out when the case is closed.
Step 10: Let's See the Mechanism in Action!
Put the rubber band joining the motor pulley with the 5cm diameter pulley and close the CD spindle case properly, ensuring that:
- The adapter wire can go out of the CD spindle case with no problem.
- The lollipop stick hole (that is attached to the base) holds the main axis.
For 2. to happen, you need to close the case carefully, observing both hole and axis. It might take a while figuring out how, but after some attempts you'll surely get it.
If everything worked well, when you plug the adapter into the wall you will see the eyebolt rotating slowly, indicating that you are ready to decorate!
Step 11: Fix the Mechanism to the Ceiling
Open two holes into the CD spindle case base so that a couple of screws can cross it from the inside. If your ceiling is made of wood you're almost done. If, on the contrary, it's made of concrete use a drill and insert plastic anchors before the screws.
Step 12: Let's Decorate!
As we mentioned in the introduction of this instructable, our focus is the mechanism. We leave the decoration part up to you. However, as promised, here we show you two different ways of decorating it.
As you see, the MDF ring (see attached files in step 6) is very useful to hang Christmas decorations. You can also hang a big Christmas ball directly from the eyebolt. Finally, don't forget to paste Christmas ribbon around the CD spindle case with hot glue and finish it with a beautiful bow. Plug the adapter into the wall and enjoy.
That's it! Hope you have fun with it!