I wanted to update my Prusa i3 Hepestos's X Ends and I also like the way that the X Ends from the Infill 3D i3Redux look. http://www.thingiverse.com/thing:371842 https://infill3d.com/home/37-x-motor-mk52.html https://infill3d.com/home/36-x-idler-mk41.html So I combined the current functionality of the Hephestos with the looks of Infill 3D. Features: 1) Belt Tensioner. 2) Anti-backlash on the Z-Axis. 3) Opto sensor mount for X-Axis home sensor. 4) Secure clamping of the X-Axis slide bars. I incorporated a belt tensioner similar to the Hephestos design. I'm using Opto sensors on my printer and did not like the stuck on look of the sensors so I added a mounting point for the X-Axis home sensor to the motor end Anti-backlash is build into both X-Ends. I added clamps on the X-Axis slide bars to lock them in place so the tensioning the belt would not distort the Y-Axis by pulling the X Ends closer to each other. I will still create new cable chain mounts for the motor end. As always, drop me some comments if you find errors or have improvements in mind. Update 2015-07-13: Uploaded source files in step format exported from TurboCAD. Unable to test the step files integrity as I can only take them back into TC. Update 2015-07-24: Added a slot on the motor end to reach the pulley grub screws Also added some support for the front overhang of the motor end as we found that normal slicer support does not always help there. NB: The X Ends must be printed upright, same orientation as they are installed on the printer to get the best layer strength around the Z bearings. If you print them flat on their backs the there is a chance that the bearing holders will split when inserting the z bearings!!! The belt tensioner is assembled with at least a 50mm long M4 Hexagon bolt and M4 nut. There is space for a 23mmx8mm coil spring over the M4 bolt between the tensioner and the X Idler End body. Insert the nut into the back of the Tensioner Knob, you might need to warm the nut with a soldering iron(or similar) before fitting it. Next insert the bolt from the front into the Tensioner. Add the spring(if you want to). Insert the tensioner into the X Idler End body and push the M4 bolt through the hole at he back. Screw the tensioner knob onto the M4 bolt. Do not tighten it yet. Next install the Idler bearings. The belt tensioner uses 2 5x10x5 bearings as they are nearly the same diameter as my 16 tooth GT2-2mm pulley. A M3 x 18mm Allen Dome head with a M3 nut is used to fix the bearings. A 5mm OD by 3mm ID by 10mm long spacer must be inserted into the two bearings before mounting. There is some free space provided for the bearings to turn in. Install the Opto sensor onto the motor end as shown on the "X Motor End with Opto Fitted.stl" file. Assemble the rest of the motor end as normal. Add 2 M5 nuts to the X ends from below. Add 2 suitable springs and then 2 M5 nuts from above. Put some pretension on the upper nuts as you thread the Z-Axis drive through them. You don't need much pre-tension, the drive rods should still turn easily Now you can mount the new X Ends as normal on the 8mm slide bars (remember the carriage) and fit the X-Axis assemble onto the Z-Axis. Tighten the 4 clamps with 4 M3x12mm(or 16mm) Allen Cap screws with 4 M3 nuts.