This is the Idler Pulley Plate. It can be used with both V-Slot and OpenRail. The idea behind this plate is to give you a mountable yet movable plate for your Smooth Idler Pulley. This works great as it allows you to easily tension your belt. There are a lot of possible mounting configurations for this plate. This design was inspired by Barton Dring of Buildlog.net 6063-T6 Aluminum Black Anodized Finish 3mm~ (1/8″) Thick Belt Driven linear actuator examples:
