Summary

I ve made this for the Opto Endstops shipped with my Prusa Mendel Kit. These tiny Endstop PCBs have SMD light barriers and only one hole to fix. So i planed in a slot to prevent the PCB from rotating.

Todo:

a wheel for the adjusting screw.
maybe print the opto bar in an other direction, because the slot for the square nut gets filled while printing horizontal.

Instructions

There is a bit of mechanical work after printing out.

Tools needed:
Drills 3mm, 2,5mm
Drill press (if available)
Thread cutter M3

Screws:
3x M3 x 40
2x M3 x 25
2x M3 Square Nuts (mine have 5,5x5,5 mm edges)
M3 washers and nuts

one smalll spring

Build it:

finish the two small holes in the clamp bar with a 2,5mm drill. The hole in the middle with 3mm. Cut 3mm threads in the 2,5mm holes.
Drill the three holes of the opto bar with 3mm if needed. The screws have to move light.
Put two m3x40 screws through the outer holes of the opto bar into the clamps threads until they come out on the other side for ~3mm. Lock the screws ends with a nut.
Put a square nut in the opto bar and a spring between clamp and opto bar. Now put the last M3x40 screw from the side of the nuts (locking the other screws) through the spring into the square nut of the opto bar.
Fix the pcb on the bar with a screw an a nut.
Mount the unit with the clamp and another square nut and screw.

You can decide, depending of your needs, how to place the opto bar on top or downside the clamp. Keep in mind, that the adjusting screw has to point on the top for easy adjusting.

Adjust and feel fine ;)

Opto Endstop X Adjuster