[abasir]

I'm in a process of building a MPG pendant for Mach3. Not willing to pay high price for the industrial encoder, I crack open an optical mouse and found that the center wheel encoder can be easily interfaced to the parallel port to provide the quadrature signals for Mach3.

It's a 3-pin encoder (not optical) that can be used directly with just 2 10k pull up resistors. More details here http://www.9w2bsr.com/2008_01_01_archive.html