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

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 rebuil