Summary

This is a mechanism I designed for holding for the Z-axis endstop, such that the endstop is mounted to a movable lift that can be tweaked up and down relative to the clamp by fractions of a millimeter with the turn of a screw. Three hex standoffs are attached to the top piece but allowed to travel freely through guide holes in the bottom piece to keep the deck level as you turn the set screw. A spring provides upward tension to keep everything stiff. Relative to the clamp, the endstop is mounted at an angle, which gets the adjustment screw out from under the X-end bracket so that it can be easily turned from above.

To assemble it, you will need:

1. The two printed parts.
2. A M3x20mm screw and nut
3. Three hexagonal standoffs, approx 20mm long and 6mm in diameter, along with three mating screws (I use 4-40, 3/16").
4. A spring, such as is used by many people for mounting their heated bed.
5. Oh, and an endstop and the screws to attach it (I use M2x16 screws and nuts).

Note: When you assemble it, make sure to get a lot of compression on the spring. This device is intended for just that last +/- 2mm adjustment, so you don't need much coil left in the spring.

The model is parametric, so you can adjust the hole dimensions and some of the other features to suit you. Please share your ideas for improvements if you build it.

Some day, I may reach a state of reprap nirvana where my Z axis never shifts by a few tenths of a mm, but until then I find this makes minute adjustments to my Z-axis offset much easier.