This is an idler for Spectra filament drives like the Kossel uses. This is a modified version of Kossels tensioner to work with Makerslide, it has a key that slides in the front t slot of the makerslide, and a hole that allows a screw hanging down from the top rail so the tensioner can be tightened easily.This is derived from tensioner_608.scad on https://github.com/jcrocholl/kossel.gitPrint with around 33% infill, slow the print down as the key for the tslot is pretty detailed and prints better at slower speeds.Slide the key into the front of the Makerslide t slot, then put a long m4 bolt through the hole and attach to the top of the frame. I use a knurled nut to make tightening it up easier.Insert 608 bearing and thread line through over the bearing. Insert either an M8 stud or print tensioner_axle.scad available at https://github.com/jcrocholl/kossel.git