Intro: Star Map Mobile
I made star map mobile as a present for my friend who is expecting her first baby:) Star map shows the sky when they found out the baby. I put forest animals around the star map.
You can choose the date of anniversary or an event. When you turn on the LEDs in the dark place, you can see the sky map of your special day:)
I used Inkscape for designing, laser cutter for manufacturing. I put LEDs behind the star map. I used coin cell battery for power and made simple circuit. I was thinking to use three AA batteries, but I miscalculated the size, so I needed to change to a coin cell battery in the last minute.. I am uploading also my failure pictures, so you can modify and make it better:D
5mm LED (2)
Coin cell battery (1)
Step 1: Design a Star Map
I used this website The Night Sky to get star map of the particular day in the particular place. I took screen shot of the star map and imported to Inkscape.
1. Import star map to Inkscape.
2. Change the image to vector image (Path> Trace Bitmap). I adjusted brightness threshold in the level to show all the constellations are shown.
3. Edit stars. Delete all small stars (tool bar on the left> Edit paths by nods). You can drag and select stars and delete at the same time.
4. Select star map and set the line thickness for laser cutting (Object> Fill and Stroke> Fill: no Fill, Stroke paint: Black, Stroke style: 0.02mm).
5. Draw lines of constellations (thicker than 0.02mm so that laser cutter will engrave).
6. Draw a circle of the mobile shape (If you have already outline, you can use it). I made the mobile which diameter is 200mm. Set the line thickness for laser cutting (Object> Fill and Stroke> Fill: no Fill, Stroke paint: Black, Stroke style: 0.02mm).
7. Make holes to hang animals. I made hole diameter as 5mm. Set the line thickness as 0.02mm.
8. Select all and group them.
Step 2: Design Aminals
I googled animal images. It would be easy to use if you can find black and white images.
1. Import image to Inkscape.
2. Select object and apply trace bitmap (Path> Trace Bitmap).
3. Set the line thickness for laser cutting (Object> Fill and Stroke> Fill: no Fill, Stroke paint: Black, Stroke style: 0.02mm).
4. Make a hole on each animal to hang from the circle. Set the line thickness as 0.02mm.
Step 3: Create a Wall Around the Sky Map
1. Calculate the circumference of your star map. I made its diameter as 200mm, so the circumference is 628mm.
2. Draw a rectangle which width is the circumference and height is 30mm.
3. Make tab. Draw a ellipse which size is height 6mm, width 5mm and duplicate. Place three ellipses in the left edge of the rectangle. The line of the rectangle's edge should be come to slightly right of the centre of each ellipse, so that when you interlock tabs and slots, it hold each other. Select the rectangle and ellipses and make them as path (Path> Object to Path). Union rectangle and ellipses by using union function (Path> Union).
4. Make slots. Duplicate a cup holder design and place it in the right edge of the original design. Select both and make slots by using differences (Path> Differences).
5. Apply living hinge to bend the wood.
*If you don't have living hinge (Extension> Render> Living hinge), add living hinge in extension, download the extension file (Living Hinge Creator) and copy living_hinge.inx and src/living_hinge.py to your extension directory. There are many instructions how to install living hinge (e.g., How to install Extensions on Mac).
Create a rectangle which width is 10mm smaller than the first rectangle, height is the same to apply living hinge. Place the new rectangle in the middle. Select the new rectangle and draw the cut lines by using Living hinge function (Extension> Render> Living hinge). Setting of gaps depends on your material. After you create living hinge, remove the new rectangle. Set width of all the lines as 0.02mm for laser cutting (Object> Fill and Stroke)
Step 4: Create a Lid and Put Aluminium Tape
1. Draw a circle which is the same size to the sky map. Put two small holes for wiring (I forgot to draw in the designing phase, so I made holes with drill).
2. You can write a message or date of the sky.
3. Cut the sky map, animals, wall and lid with laser cutter.
4. Put aluminium tape whole inside of the wall and the lid so that it reflect the light from LEDs.
Step 5: Battery Holder
I was thinking to use three AA batteries (1.5V*3) to turn on two LEDs in parallel (3V) with 75Ω resistors. I modified the battery holder from here: AA-Battery-Case. But I miscalculated the size, it was too small and while I was trying to fit three batteries, it broke.. I didn't have much time to fix it, so I changed to use a coin cell battery instead of AA batteries without resistors. The light is less bright but it is enough to see in the dark place with diffusion effect of baking paper. Of course you can modify the design and use AA batteries if you prefer :)
Step 6: Attaching LEDs and Wiring
I put two LEDs in parallel on the surface of inside of the lid.
1. First, I attached LED on a small piece of MDF. It is easier to glue it on the surface of the lid. Solder the longer leg of LED and red wire (which goes to plus of the battery), and shorter leg of the LED and black wire (which goes to GND of battery). Create two sets of this.
2. Connect two red wires and add another red wire. Solder three wires and fix them with tape. Same as black wires. LEDs are now connected in parallel.
3. The red wire and black wire that are added go to the holes on the lid.
Step 7: Switch and Coin Cell Battery
Now you have two wires (+, -) from the holes on the lid.
The structure of the switch I made is two layers, -wire is attached on the bottom layer with aluminium tape and +wire is attached to the small lid of the second layer as button. So when the small lid touches the aluminium tape on bottom layer, + and - are connected and LEDs turn on.
*Since it was very last minute change to use coin cell battery, the design is not the best one. You can modify it as better. I made switch and coin cell battery holder as two layers, but you can add one more layer on the top to hold the battery.
Step 8: Assembling
1. Use strings to attach animals to the holes on the sky map.
2. Use wood bond to attach the wall to the bottom (sky map).
3. Glue switch on the surface of the lid.
4. Glue LEDs to the other side (inside) of the lid. Angle of LEDs should be set as it light the wall, not the bottom (inside of sky map). Aluminium tape will reflect the light.
I did not glue the lid to the wall, but you can glue it if you prefer.
5. Cut baking sheet as the same size to the sky map and place it inside. It diffuse the light of LEDs.