This part goes with my other part (http://www.thingiverse.com/thing:985629) to make the y-axis much more rigid and easier adjustment for belt tension. This does require you to drill 3 holes in the frame, so do at your own risk. Measure twice, drill once! Once again, Inventor did not size properly.. The bracket dimensions need scaled x10(20mm,10mm,24,2mm) The mount dimensions need scaled x10(52.1mm,24.5mm,15mm) The improved stl needs scaled x.01(20mmx,30mm,20mm) its ridiculous I know :/ I printed this in abs, as it what I normally print with but I assume PLA etc should be fine. Some of the holes may need a slight Dremel/drill here and there as hardware isn't the same everywhere. 1) For the most strength I recommend printing the parts as if they were going on your printer(as is top is top, bottom is bottom etc) 2) I used some hardware laying around for the bolt, which in my case was a M5x40mm hex bolt with a wingnut 3) Re-use the stock bearings etc, but for the tensioning bolt, I had to squeeze it in place by tightening the wingnut down and forcing the bolt into the plastic. Should be fine if using a m5 hex bolt. 4) The mounting holes are 40mm apart, I drilled mine bigger to allow fine tuning the idler. Do the same for the hex bolt.