Printrbot Simple 1405 M8/M5 Z-Nut

thingiverse

This upgrade kit lets you switch from a standard ACME rod to a metric M8 or M5 rod using a "captive" nut that's integrated into one part. I designed this solution because z-banding issues plagued my printer despite no apparent common cause, so upgrading to a beefier metric thread seemed the way forward. Instructions: The nut isn't truly captive but rather inserted into one component, which is then attached to another piece. Originally, this design utilized a captive nut, but alignment problems arose. Before starting the upgrade, you should obviously print these components using your current setup settings. For the bottom part, any rigid material will work. I used Colorfabb XT since it happened to be loaded into my printer at the time, but PLA will also get the job done. For the top piece, a flexible material is recommended. I used Formfutura's FlexiFil, a rubber-like substance that worked beautifully for me. When I attempted to use a rigid filament initially, I encountered difficulties getting the nut to align properly. In terms of hardware, you'll need two M3 10mm screws, which originally held the delrin piece in place; these will secure the bottom part. You'll also require two M3 16mm screws for attaching the top component to the bottom piece, an M8 nut, and an M8 threaded rod with the desired length. If you want a replacement stepper coupler, I suggest using this M8 version: http://www.thingiverse.com/thing:533928 First, remove the old leadscrew mechanism by undoing the set screws holding the rod in place. Then, thread it out of the delrin piece (indicated with *) in the y-z assembly. Unscrew the two M3 10mm screws that held the original delrin piece. This is an excellent time to swap out the coupler on your stepper motor. Next, mount the rigid bottom part using the two provided M3 16mm screws. Insert the nut into the flexible top component and attach it to the bottom piece with those same M3 screws. Finally, pass the M8 rod through the new nut-assembly, secure it in place within the coupler, and enjoy your metric leadscrew system! Remember to update your steps-per-mm setting; 2560 is now the standard value (see comments for further information). (*) If you own a Simple with the standard size y-z assembly rather than an XL model, you can easily unscrew the delrin piece directly instead of having to remove the threaded rod from it.