• experimenting with Kevlar thread inside PTFE tube bowden

    István Nótai • 04/09/2018 at 10:17 • 0 comments

    I made a bowden cable using 1.8mm Kevlar thread and 2mm inner 4mm outer diameter (3d printer bowden tube for 1.75mm filament) PTFE tube, with a thread cutting tool I cutted screw thread on the outside of the tube to make it grippy, then i glued the tubes inside the holes of the housing, then the Kevlar thread are connected to the pulley's reel.

    I like the Kevlar thread approach beacuse Kevlar is lightweight and has a similar tensile strength by diameter to steel and more importantly I can easily bend the thread low radius, so I can make a reel smaller than the pulley to increase the transmission ratio, without using another pulley.

    The pulley and the reel works well, but the PTFE tube is trying to collapse if I try to lift more than 3kg.

    It looks like I have two options: change the PTFE tube to steel bowden housing or using another pulley and a bigger reel to move a fully steel bowden setup.