You can buy coolant proof steppers (just found some online the other night) but they don't go nearly as high in torque - they're intended for food processing and the like. I'm going to take the same route Hoss did with bent plastic, though I may start off with something a little less elegant - I drink a lot of prebottled juice and the bottles are just the right length to cover my whole shaft connection to the end of the stepper and beyond. Warm it with the heatgun and it will mold to any shape you want - much what the R/C guys do to vacuform cockpit covers and the like. Hmmm - maybe I'll make a mold and do a vacform with the bottle plastic...
Silicone is great for the wire connections/entrance but the bearing and shaft holes are still open. I'm not going to get too exotic as I don't plan on flood cooling just the errant chip guard really and wipe up any mist which might deposit.
And to respond to 300magnum's question - No they are not liquid proof.
Every day is a learning process, whether you remember yesterday or not is the hard part.
www.distinctperspectives.com