[billbo911]

Originally Posted by techhelpbb

Had nothing but trouble with the US Digital encoders like the one you linked.
Years of trouble.

Many teams swear by them we simply can't have any more surprises.

DigiKey sells may fine encoders that are slightly more expensive.
If, like me, the time you waste playing with the encoders in the end is way more valuable than the encoder I would go shopping at the higher price.

One hour of my time more than buys all the encoders we are likely to need from a company like GrayHill.
Further it reduces this when someone suggests using an encoder.

Our experience with the US Digital encoders is mixed. They work very reliably when handled and installed properly. But, as hard as we try, working with High School students, that is not always possible. Disk get dirty, smudged, and misaligned. Shaft run-out and end-play will destroy the little US Digital encoders in a heartbeat.

Don't misunderstand me, US Digital makes some fantastic encoders. It's the ones linked to by the OP that can be a bit suspect.

A sealed encoder that is mechanically isolated from motions that can damage it are your best bet.