A simple retainer plate for a $2 well nut. You can use the existing holes on the platform, you don't need to drill or thread anything -- this was the simplest approach I could find/think. Also, the rubber should act as a spring, which is nice (I guess). I have one of the new aluminium platforms, so previous fixes needed modification. Credit for this approach (which was the simplest I found) goes to http://www.soliforum.com/topic/2341/poor-mans-antibacklash-nut-no-assembly-required/, but the new platform has nothing there to jam the nut against, so I made this retainer plate. Backlash on the new platform was minimal, but it was there. This seems to eliminate it nicely. We'll see how well the rubber holds over time (but for $2... who cares :). Update 11/9/13 Added observations, after about six months of use, into instructions.Note that you have to insert the well rubber nut brim downwards (not up, as in the forum post). In this orientation, the rubber might also work as a spring. My Z-rod is just the right length (<1mm shorter and the nut would start coming off when Z-axis is homed -- wheww!) Works nicely so far. PS. The screw holes have a countersink, because the 4-40 screws I had were a bit short. You can edit SCAD source if you're worried about strength. Based on reports from other people, it seems that not all rods have equal length. If yours is too short for the depicted installation, you're out of luck, sorry. After about six months of use, it seems that my original theory on how this works was off. I install the well nut by tightening. The idea was that this would make the rubber work like a compression spring. However, observations do not entirely agree with this. Tightening the nut makes the rubber bulge a bit (btw, you don't need a wrench--actually, you can overtighten to the point of binding the axis even with fingers, so be careful). It seems this makes the rod threads "bite" into the rubber, which is what removes the backlash. Since the rubber is compliant, the axis won't bind. However, there are still stresses on the rubber which, over long period of time, will make the nut come loose (you can observe this if you mark the original alignment of nut and retainer with a permanent marker). As the nut loosens: (i) the bulge will diminish, making it slightly less effective at reducing backlash, and (ii) the rubber base will expand in height, creating stresses that after months may crack the retaining plate at it's thinnest part. I currently deal with this by just re-installing the nut every few months (works for me..). Other idea: instead of tightening the nut, leave it a bit loose (and tighten plate instead) to make it work like an extension spring instead (hopefully). I haven't tried this, and I have my doubts if the rubber (esp. at the base) is rigid enough to make this work. If you do, please describe experience in comments. I've also uploaded a modified plate (v2) which should be stronger and hopefully last even longer (currently testing, will update with observations in a few months). The plate also has fixed hole placement (X-distance was off by 0.5mm in original) and I'm now using 8mm M3 screws, with washers.