Melting PET for something useful

31 Jan 2006 It's noot's birthday today ! This morning I got up and hung his door full of balloons. I have a crappy picture that I took with my GSM, and maybe I can upload it to here soon.
(Did I already mention that I *finally* managed to download stuff from my GSM with bluetooth?)

Anyway, yesterday we were talking about the telescope noot is building. He's going to motorize it and mount a camera on it so that the thing can track stars and take pictures with exposure times of several hours. Sounds cool, especially when you realise that all great astronomical pictures are created this way. The more exposure time, the more light you catch, the more detail you have. All of this of course, if you keep the telescope aimed at a specific point. Because the Earth rotates, you need to counter that movement by automatically rotating the telescope in the opposite direction.
That's why a motorized telescope would be cool.

To motorise a telescope, you need a telescope, a motor and some cogwheels and electronics.
I suggested making the cogwheels ourselves by melting PET, and I got to looking at the whole thing again.

I found this site: http://www.goedjn.com/essays/botplas.html

This guy has been experimenting with PET more than me (mostly because he has an oven that is hot enough).
His findings are that melting PET is probably not the best thing to make something. But I don't give up that easily.
I've been thinking about the whole molding plastic story, and think that I could make some nice stuff if I suck the mold vacuum as I inject the plastic. I can suck it vacuum by hooking it up to a vacuum cleaner. This would make a nice experiment :)

I also found references to some Sky & Tel articles from the 70s (http://ftissera.free.fr/Webmel/homemade_gears.html and http://astro.umsystem.edu/atm/ARCHIVES/APR96/msg00414.html). From what I've read, they sound promising to do stuff like this. I can't find a lot on the internet, so maybe I'll have to visit the library sometime. I have access to the university libraries and I haven't been making use of that privilege much :)