Here's to all of us that have the Printrbot Simple with the XL Tower / Build Volume Tower Upgrade. Where the filament goes to the left and slips off the extruder bearing... This solves the problem by forcing the filament to the right. Also I found that the printrbot bearings were too far offset for my other spools so I created a simple rectangle to hold the two bearing holders from Small Spoolholder by JohnSL (http://www.thingiverse.com/thing:93652) This filament guide is mounted using the same allen screws from the Simple kit (you should have some extra) with drilling a 5/64" hole. The dimensions of the mount hole are: 5.9mm countersink diameter with 3.75mm countersink depth. The inner hole is 3.75mm to clear the screw threads. This is oversized a bit to accomidate shrinkage from your printer. Good luck! Rotate X 90 degrees to print flat Slice using typical settings, nothing to crazy here and .3 layer height works great. Be sure to have good bed adhesion as the end loop can get distorted (blue painters tape with a swab of 91% isopropyl alcohol works great for PLA!