Another way to make encoders

[andypugh]

I recently got some Avago AEDR8300K encoder sensors. These have two detectors in a small SMT package for quadrature in one device.
Reflective Optical Encoder
My plan was to laser-print a target onto adhesive vinyl and use that as the target, but unfortunately it seems that these sensors require a very shiny target (specular reflectance > 60) with not-shiny parts. White paper is "not there" to these sensors.
Polished aluminium is very much "there" but so is polished aluminium with black marks on.
After some experimentation I found that polished aluminium with an etched pattern works very well, though. So I CNC-marked a polished encoder ring and etched it in FeCl. This looks like it is going to work very well indeed, and was a lot less trouble than milling (and more suited to the dimensions of the part)
Encoder - YouTube