[MonoNeuron]

My Grandfather had something like this on his pushbike axles to keep them clean,
It's just leather shoelaces wrapped around the screw twice and close to the nut with a small weight hanging from them and in this case it's a 20mm nut. As you can see in the picture they do a great job and only need to be cleaned about once per year and oiled.
Do any of you out there have something similar? It's an old fix to a new problem. I've been using them for about 5 years now and they are still the same ones so should last a life time.
Richard.
PS. These would also work on the Z axis if you had a small bracket with a spring pulling to the side of the screw. Poor mans wiper seals that work a treat.

[wizard]

Interesting idea!

I would worry about crude build up in the leather leading to more wear. However keeping the ball races clean is probably more important. To be honest im surprised that the leather doesn't work its way away from the ball nut.

You say you have five years on these which is impressive. If that is all you have done to keep those screws shinny then this is a technique worth considering especially for those doing dusty materials.