Since I'm Dutch, I often bike because it it so convenient in this country. I have a cheap bicycle for years and so some of it features need some upgrading. The standard bike light it came with died pretty quickly because of water entering its housing. Instead of buying the umpteenth cheap boring bike light, I wanted to create my own with a interesting form.
Therefore I edited a 3D model found on Thingiverse to create an eerie looking raven skull bike light!
Step 1: CAD 3D Models
For the main body of the raven skull I edited I used a STL model from Thingiverse that I could edit for my purpose.
The original file can be found here:
This file I edited with several software programs to split it in two, to make it hollow, create the attachment point and to create the eyes.
The battery compartment consists of three parts which are designed around a standard battery holder from a used bike light (see step 3).
All the modified models I created are available on Thingiverse at the following link:
Step 2: 3D Print Files and Paint If Desired
Print al the files with your slicer and printer of choice! Both the skull and the eye need a mirrored counterpart. All conventional slicers support this. I use Cura as my slicer of choice.
I used PLA for the skull parts. The eyes are printed with green, translucent PET filament but you can use any translucent filament of choice. I enabled support since the skull parts are hollow. The eye parts don't need it. It can be interesting to experiment with different kinds of infill for the eye since light will shine through.
A good tip is to first print the skull and then one eye. If the eye doesn't fit snugly in the eye socket you can scale it the eye model a little bit in the slicer. Print again and check if the fit is better.
The eye follows contours of the socket, so turn it around to find the correct fit.
The battery compartment contains of a box with a lid, really basic. They could be scaled in your slicer to fit your own battery or battery compartment.
The skull parts are painted with a few layers of primer, sanding in between layers for a smoother surface finish. I spray painted them black for the base color.
Step 3: Harvesting Parts From Old Generic Bicycle Light and Modifying Electronics
My cheap bike came with a generic bike light that runs on three triple A's. It wasn't particularly watertight, water entered the battery compartment and bricked the batteries. There wasn't any rust though on the inner parts of the light itself though so I could still use it.
The board is very simple and should be pretty similar to most layouts in a generic bike light. Mine had three LED's on the board that were powered on three triple A batteries. I removed one LED and replaced them with a couple of resistors that more or less equals the resistance of a LED.
Another modification I made was to extend the LED's and battery holder. I removed the necessary connections on the board with a soldering iron and put wires in between to lengthen everything.
Also I removed the switch that was directly sitting on top of the board. I replaced it with a bigger rocker switch and again running some wire between the board and the switch.
Step 4: Installing Eyes and LEDs
Once everything is printed, base painted and dried the eyes can be put in the skull halves. Tolerances can be tight so I applied glue to the edge of the eye and held them in the skull sockets with a clamp.
Make sure that the electrical connections are still working each step of the way by testing the light!
After that, the Led's can be placed and glued into the fitting holes in the eyes.
To maximize light shining outwards, I applied a couple of layers of white paint on the back of the eye. To seal everything of I applied a couple of layers of black paint. A layer of aluminum foil could do the same trick.
Make sure the eye is glued water tight in the socket. The end result should be able to handle some rain.
Step 5: Assemble Skull
Next up is to tuck all the necessary electronics inside of the skull halves, running the wires through the hole and close it all up. I used two component epoxy glue to adhere the two skull halves together. Make sure that all of the seams are properly glued to ensure water tightness.
Again make sure all the electronics are still working before gluing anything down.
I used some generic wood filler to fill the seam between the halves, sanded it down and add some more paint for a smooth finish.
Step 6: Seal Up Cable Hole
I used some black silicone kit to plug the bottom hole where the wires exit the skull.
Step 7: Copperplate Skull
To make a really cool optional finish I copper-plated the outside of the skull (of course you could easily spray paint the part in any color you like). There are several methods on doing this but the basic principle is to use an electrically conductive cover on the 3D print and use an electric current to move copper from a copper cathode to the 3D printed anode through an electrolyte. There are several good videos on how to do this on Youtube. I got part of my recipe from this one: CNC Kitchen copper plating
-Tape the eyes before spray painting. Paint the 3D print with 2 to 3 layers of zinc spray. Zinc spray can be bought in most hardware stores. This alkyd paint spray contains a high level of zinc particles and can create a conductive coating on plastic 3D prints. Make sure to give the paint at least a day to fully dry.
- Prepare the solution. I used a solution of 4 parts of distilled water to 1 part copper sulfate (in mass). I ordered the copper sulfate online. Add a table spoon of salt to finish the solution. Better solutions can be made by adding sulfuric acid, but I had proper results without it. It is important to use distilled water. It can be bought, but I made my own by by following one of the these methods: How to make distilled water
! Don't flush the solution down the drain as it is quite toxic to the environment, discard of it properly at your local waste/recycling center !
- Connect a power source to the 3D print and to a copper object. There is probably a proper way to determine what the best power source could be, but I had good results using a 12V adapter rated with a maximum current of 1500mA. In any case use a relatively low voltage DC power source.
- The negative lead connects to the zinc covered part that you want to copperplate. Wind the stripped wire from the DC source or tape it onto the part. Connect the positive stripped lead wire from the DC adapter to a copper object. I used a copper plumbing pipe.
- Submerge the part and the copper in the solution and make sure they don't touch each other. After an hour or so, a side of the part should be covered in a thin layer of copper. Turn the part around a few times to cover the different sides of the 3D print in copper. Any oxidation layers should be removed every now and then.
My result was far from perfect, probably because the partly submerged part and the lack of sulfuric acid. But I was happy with it for a first try! Also, it may be better to copperplate the two plastic body halves first and install the electronics afterwards. If a leak exists it could damage the insides.
Step 8: Sand and Polish the Copper Plating
If the surface is properly covered with a small layer of copper, it can be cleaned and dried.
To create a shiny finish sand all the surfaces down starting with a grid from 400 and finish around 1500. Be careful with coarse grids, as it can tear of small layers of copper.
As seen on the pictures, my copper coverage is not perfect but I like the overall finish. Before installing it on your bike and using it, a few layers of clear lacquer should seal everything neatly and prevent it from rusting.