Thanks for the compliment and the link,
We used a .032" BEM and it was at a .125" total depth. You said pot, I assume your talking about the US Digital MA3 shaft encoder we are rotating with the 4th axis servo motor. They are very reliable. On the first analog modulated laser engraver we built, there's over 1200 hours on it. We only had to replace the 1/8" wide Kevlar reinforced timing belt on it once. Our servo machine in the video has about 250 hours on the encoder since we built it.
Jeff