This is part of my mini-R2D2 project. I intend to keep blog pages for the different parts of the building process.
The dome is made out of a clear plastic sphere. I found 2 globes 16cm in diameter and 2 smaller ones 4cm across.
First step. Dremel off the bit that is sticking out and sand the whole thing.
next: find the exact center of the hemisphere and drill a small hole. The hole is handy for hanging it up when spraypainting and it is used in conjunction with a flexible piece of plastic to draw perfect circles on the dome.
After a lot of puzzling to get all the panels drawn more or less neatly with a marker, I used a sharp skrewdriver and a knife to cut the edges of the top panels. That way, the edges will still be visible after the dome is spray painted. I choose to paint the top panels with a brush, because masktaping and spray painting those, doesn't turn out as nice as I had hoped.
For the side panels, I marked the start and end points on the ring the dome will be mounted on. Right now I'm cutting those panels from a sheet of 0,5mm PVC. The panels will be painted and glued on later. I hope that the paint will hold on the larger panels when I bend them onto the dome. if not, I will just paint the edges of those panels, glue them on and paint the middle afterwards.
As you can see I got started on the radar eye. The housing is cut from a piece of 8mm thick expanded PVC. I used boiling hot water to make it soft and then I pressed it against the dome to make it curved. I used a knife and a dremel with a cone shaped sander bit on it to make the hole and the side bits.
The eye was done by roughly cutting out a piece from a small shiny hemisphere, sanding the edges and then using a black marker to darken the inside. The black eye is wedged in the housing, but can be removed. After the housing is spainted blue, it will be glued in.
update: first paintjob on the top panels done.
Update april 20th: Disaster hits! it turns out that cutting out the side panels, painting them and then glueing them to the dome was not a good idea. It is allmost impossible to get those cutouts aligned properly and on top of it all: the glue disolves the paint. Starting with a tiny blue smear that could be removed quickly, one bad correction led to another. Now I'm not sure what i'll do, but this is not looking very nice.
On the surface it doesn't look all that bad, but the spay painted silver, will never look nice and neat like before. I do have silver colored marker that can be used for small touch-ups, but this will never look really good. Maybe i'll cover all the blue bits and carefully spray paint over the nasty bits or maybe someday I'll make a new dome and carve all the panel edges and hand painting all the blue panels instead of just the top ones.
But, as I read on another r2d2 builders tips and tricks page, no matter how much you skrew up, it will still look like r2d2. So for now I will just clean up as best as I can, add the lights and motor and continue on the body work.
Update : april 22nd: More uglyness with the dome. LED holes were badly aligned and on top of that: I spilled a large drop of paint disolving glue on the dome. I used a marker to sort of correct this, but I'm going to be taping up the blue parts and then spray painting all the ulgy bits of dome sometime soon.
Still; I added a few lights and I improvised the motor for the dome. A small geared motor with a fat rubber tire. For now the motor is taped to the upper disc. I'll figure out a better way of fixing the motor later. I put a piece of PVC tube in the middle of the lower disc with the top disc sliding over that. I can run wires through the pvc tube to the robots body.
Motor taped to the upper disc. The motor is connected to some servo electronics I ripped out of a broken servo. for now I connected everything to my picaxe 28X starter board.
So far: 7 individually controled LEDs and one servo-style controlled motor. The motor is slipping a lot now, but adding another guide wheel on the other side will fix that.
Also: I need to add IR sensors to determine the dome's position.
The front eye is not lit yet. As it turns out the LEDs I have are simply not bright enough to make a nice coloured circle through the white paper in the eye. I'll have to order red and green LEDS that are way brighter.
front logic-displays are 2 dimmed blue LEDs and 2 dimmed white LEDS. I used 10K Ohm resistors to prevent them from shining too brightly.
In the test program I flash them randomly very quickly which gives it a somewhat nervous look. Anyway: the 4 LEDS in front and the 3 (red green yellow) LEDS on the back of the dome are controled individually so there are lots of ways to turn R2D2 into a happy flashing disco bot.
Update july 15th 2013 : The dome is now half operational. I "mounted" my picaxe 20X2 board with a few drops of hot glue, mounted bright leds for the front eye, replaced the motor with a continuous rotation servo and added a piezo, a photoresistor.
Thanks to a tip from 6677 I added a sheet of sanding paper for the the motor, that doesn't slip so bad anymore. I also added three guide wheels that lift the dome 1 few millimeters. Downside of using the servo: it is very loud, but I am using the other motor for driving the robot itself. With this setup the dome rotates well even when it is tilted.
An IR LED with phototransistor is added to detect the NULL position of the dome. In the second video, you can see it resetting to forward position. When the Raspberry is added inside the body it will use a speaker to make better sounding R2D2 bleeps.
The dome is controlled with I2C, but I also added a small routine that runs when no I2C master is controling it.
https://www.youtube.com/watch?v=o4HiIOObf6Y?hl=nl_NL