I don't like those Y axis rolle. There's too much play in it, so I made this ^^^ to go with this 400mm linear bearing..... It will mount on the outside of the 20x20 aluminum with M3x7mm screws with T-nuts. M3x7mm will work to mount the piece to the block as well. This will work with a stock X5S or one with any one of my upgrades. Added X Y Gantry to go with You will have to put some Top Z Axis mounts to lower and give the threaded rod bearing clearance. Use the one with the flat side on it facing out. You should really upgrade that anyway even if you don't use this ^^^. UPDATED 1/28/2018 I finally got all the parts and I had to change it up a little. According to the data sheet the bearing block should have been 45.4mm when in actuality it is 49mm. UPDATED 2/2/2018 No longer supporting stock pulleys. They're garbage. I'm now running wide open with no missed steps and high precision. You will need these 2 upgrades to work with this setup. Corner Pulley Mount: and X Y Motor Mounts: Updated 2/13/2018 Added an SCAD file that is adjustable for pulley center distance from center of 20x20 & pulley distance center to center from each other so you can compile your own custom gantry brackets to match whatever X gantry, corner pulley or motor mounts you have. It's also adjustable for skew angle to square up your prints and make your printer kick ass. Read the SCAD file header for info and address any questio to the comment section. Updated 4/13/2018 Added X Y Gantry because some of the blocks ARE 45.4mm & not 49mm like the fit ones I ordered. See above edit 1/28/2018 Updated 7/18/2018 Added the ability to change pulley screw size to the SCAD..... Added AdjustableX Y Gantry*****'s at PuddingBaer91's iistence for use with these. (see link below). I already made mine and they are working fine so I don't see any reason to change it, but if you haven't built you yet you may want to coider this option. It's a good idea..... zu M5 hülse&_from=R40&rt=nc In addition to these you will need M4 hardware according to these specs.... Radius of bolt thread is 2.1mm (for M4 screws). Screw and nut radius are 3.93mm (already added 0.2 to 7.66 and devided by 2, this is now for M4 DIN screws). Depth of screw head are 2.8mm and nut head are 3.2mm (also for M4 DIN screws).