Because my Comgrow dryer sits above the printer, the PTFE filament guide puts a lot of stress on the print head, causing step skips and can even pull the dryer over. Therefore, I replaced the through-threaded tube with this pulley and bearing (but, it's a WIP). I've had good luck printing the stiff parts in PLA or ABS and the flex parts (axle, guide) in PETG. If you choose the 608 bearing below, a 2-layer raft and 0.25 nozzle work well (it still requires some manipulation and working to break all the little fibers and get the needles and race loose). The M8 thread was just right with 0.4 nozzle and 0.2mm layers. Required M8 plastic nut and PTFE tub from the manufacturer's filament guide 608 PiP Half Cage Roller Bearing or another 608 bearing.