I am completely incompetent with dithering so was thinking of doing a study of it just like this. I liked it, it really got a lot of texture. I am a little uncertain about the shape of your gear, specially its profile, was it supposed to be smooth or should it be sharper and the smoothing is a side effect of the dithering interfering on how you would draw its outer border?
Also, is the "flat" surface which holds the face slightly curved for you to get those lovely dithering bands or was it supposed to be flat and you applied the dithered lower light as reflection?
Just some thoughts on it, I liked it a lot, mostly the background dither pattern.