Micro Adjustable Bare Wire Z End Stop

thingiverse

This is a micro-adjustable bare-wire end stop for reprap printers (or any other machine that could use it). You can also just glue a switch to the top of it if you don't like the bare wire idea. It attaches to the Prusa end stop holder, and is assembled with a spring, M3-30 screw, nut, and washer. A twisted pair set from an old network cable is exposed atop an adjustable surface and makes contact with another bare wire on the X end. This endstop is ridiculously inexpensive, and it allows very fine adjustment of the Z stopping position by turning knob at the bottom -- one full revolution is 0.5mm. I have the OpenSCAD sources for this, and there are actually a number of adjustable parameters. I need to clean the code up a bit and then I'll add it. You can find my basic "one penny" bare wire end stops here: http://www.thingiverse.com/thing:23878 Instructions 1) Print the three parts. (It's pretty quick.) 2) Assemble the adjustable end stop. (Refer to picture.) There is a base, a knob, and a cap. The base is the part that clips onto the end stop. Drill out the holes on all three parts if necessary so the screw slides though easily. Melt an M3 nut into the knob with a soldering iron. Place the screw through the top of the cap, then put a spring onto the screw, and then add the base. Orient the cap so that the guide rail slides along the bottom (usually smoother) side of the base. Add a washer or two, and screw the knob onto the exposed end of the screw. The knob hides the end of the screw as is adjusted. Be sure the parts move freely, and clean them up a bit if they don't. Kapton tape can help it slide if necessary. 3) Wire it up. If you want to use bare wires, drill tiny holes (e.g. #60) through the side of the cap, on either side of the screw near the base. Notch the ridges at the top of the cap with a file to accept the wire. Loop wire through holes, over the top, and then tie them off where the entered the sides. (Refer to photo.) 4) Install it. Be sure your hardware is set to use a NO (normally open) end stop for this axis. Fasten a bit of exposed copper wire to the X end and be sure that the wires on the end stop come into contact with it as it drops. (Refer to photo.) Use electrical tape to take up slack if it doesn't fit snugly. Wrap the wire around the end stop holder for stability. 5) Enjoy your ridiculously inexpensive, wildly accurate, and finely adjustable Z end stop. :) I haven't had to yet, but you'll probably need to clean the wires every once in a while. A quick scrape with fine sandpaper will probably do the trick.