Z-Nut Anti-rotation for Plus

[RetireeJay]

I recently installed new nut holders that I designed. These may or may not fit in your machine. But the idea is to eliminate the possibility of the nut turning even a small fraction of a turn within its well - yet still allow the possibility for the nut to "back out" of its well if the printhead lands on the bed (or some obstruction).

Print two of these at 100% infill, and very fine layer height (0.15 or 0.1mm). Then use fine sandpaper to smooth the curve even more. Use sandpaper or a file to remove all burrs and flash; get the dimension from the curved side to the flat wall as close to design as you can: 10.16mm. Lubricate. I glued these into the well with a small amount of silicone glue (using a nut during curing to hold good pressure on the part, so the layer of glue did not throw my dimensions off).

It will take a little force to get the nut to enter the space between the new part and the opposite wood wall because we want to have a spring action that perfectly immobilizes the nut from rotating. I printed mine with Taulman T-Glase because that's what I had in my extruder - but nylon would be a little better because it's more flexible. It will probably work with whatever plastic you use.

Z-nut Insert.jpg

The piece will put the nut into a "vise" between the plastic insert and the outside wood wall, so the nut can't rotate.

[plexus]

I printed these with ABS for the same reason, its what i had loaded. Seems to work well. Thanks RJ this is an excellent mod!

[thoughtfix]

For the Plus V2 1306 with the Z-X upgrade, printed this: http://www.thingiverse.com/thing:363880
Also purchased the matching DumpsterCNC anti-backlash nuts, flanges, and couplers. They made a world of difference in my Z accuracy.
WP_20140819_18_51_06_Pro.jpg

[RetireeJay]

I'm glad that this helped you. But I have two observations:

1) It looks like your setup has no "safety release" in case the Z endstop doesn't get actuated (an event that has happened to me more times than I want to count). The lack of a safety release could lead to extremely high loading on the hot end when it touches down on the bed. The old standard method of nut capture allows the nut to "back out" of its cage and leave only the weight of the carriage resting on the extruder with no EXTRA force being generated by the motors.

2) With all the weight on the X carriage and extruder pushing down on the Z nut, there should be no need for any further "anti-backlash" spring to "pre-load" the nut. It's loaded already, and the force is always in the same direction. At least that's what I have found. YMMV.