X-idler Mount Plate with X-axis belt tensioning for Makerfarm i3v 10"

After putting my original design of this on my printer, I realized I could add a belt tensioning adjustment by changing the hole that the idler screw goes thru to be open on that end thus being able to slide the idler pulley along the x-axis to tension or lossen the belt. See http://www.thingiverse.com/thing:866648 for more info about the original design. This will probably work for the 8" & 12" version. The eccentric spacer holes are countersunk, so you do not need a washer where the lock nut