Here is a detailed video by Peter, showing the computer aided design version of the 1227 anglepoise lamp. I started it in the link at the point i found most interesting. If you want to see it all just press replay on video control to start from beginning.
There is also a link to a cad file, for free, (his website does go up and down a little, please be patient)
I like the way you can see the angle between the springs and arms and the component assembly is very clear.
use this if your thinking about making bits from scratch or you have missing parts to make. This gives you a good idea of shape and function (keep it in mind this is for a newer shape and is the giant).