Adjustable Z Endstop for Prusa i3

thingiverse

One of my early printer modifications was adding an adjustable Z endstop (http://www.thingiverse.com/thing:149882 and http://www.thingiverse.com/thing:1253186) to my Hesine M505 Prusa i3. The new setup worked well initially, but a later X-axis upgrade (http://www.thingiverse.com/thing:1103976) created an alignment issue with the Z plunger and endstop switch. I redesigned the original mount to fit the new motor mount's configuration. Then, I reworked the offset adjustment plunger mount for improved switch contact and screw tensioning. This design is a result of those changes. The Z endstop and offset mounts are easy to install as shown in the attached images. The plunger assembly requires some explanation since its internal components aren't visible. I believe the adjustment screw and nuts used were #6, sourced according to the original design. The 3-inch-long screw I chose has a specific length for this application. To assemble the offset mount, place a nut on the adjustment screw so about 5mm of thread extends past it. Then, insert another nut into the bottom of the mount. Next, install a small section (about 8mm) of 3/8" compression spring over the end of the screw, resting it on the nut. Insert this assembly into the top of the mount and compress the spring while screwing into the nut at the bottom of the mount. For the plunger, attach a nut to the recessed area and then glue the bottom piece in place. This traps the nut inside the assembly. Next, screw another nut onto the end of the adjustment screw with about 4mm of thread extending past it. Then, attach the plunger assembly to the end of the screw using the nut for tightening. To access the mount holes to attach the offset assembly to the X-axis motor mount, you'll need to screw the adjustment screw in as far as possible.