Printrbot Simple 1405 Z axis wobble stabilizer and z-ext acme nut

thingiverse

update 2/7/2016: new v3 version that is flexible via a slotted design. This should let the piece fit tightly while allowing some tolerance for varying print quality. I'm using the 8mm version, which should work fine for most printers. If you're prints are horrendously wobbly or otherwise inaccurate that a hammer wont make the 8mm fit, there is also an 8.2mm version that fits less tightly over the bars. update 2016: Despite the top cap previously seeming to improve my prints, after rebuilding my printer to replace the acme z nut i once again had very poor sidewalls. I have again achieved nice sidewalls. The difference seems to be in the Z-coupler, which I had to adjust many times after the rebuild to get good prints again. I currently have a very small amount of separation between the motor shaft and z-rod, about 1mm or less, and had to reseat the z-rod at this height many times, rotating a little relative to the motor shaft each time and doing a test print, before I once again had good walls. V2- now uses a screw on shim to prevent the cap from getting screwed off while also holding the rod tighter. Also added a new z-axis connector thing that extends further down the threaded rod as the original (mine at least) had some slop. Intended to help correct banding on prints. Shimming the bars with a wrap of tape will keep it from screwing off and help with snugness. Also, for anyone trying to get rid of banding my biggest improvement was making a gap between the motor shaft and the threaded rod in the z coupler; my z axis now has about a 1mm of springy movement in it if i push down on it before the threaded rod hits the motor shaft. http://d17kynu4zpq5hy.cloudfront.net/igi/printrbot/nWxUaH1eEPnsiGCT.standard See the middle "2" picture for what I mean. ignore the "bad' label