Z slides can slide off rails

[wabmester]

There is a stop at the top of the Z rails, but there's a gap between the bottom of the rail and the motor bracket. The slide (and ball bearings) can move into this gap.

[mikeabuilder]

At the top, we can the aluminum retainer is less than 3mm above the end of the rail. we can drop it down to touch (or nearly touch) the end of the rail. On the bottom, we can design a printed plastic part that connects to the 4080 aluminum with a T-nut and prevents the carriage from sliding off the end. We can also create a place to fasten a microswitch that can be used as the Z-Max end stop.