This "Itcher" is an improved extruder with a significantly improved grip. It is designed for the Ormerod using pneumatic bowden fitting and PTFE support.

Different as Mason Stonehendges´ spring loaded extruder the spring is loading primarily the pressure of the hobbed to the filament (and NOT primarily the pressure between the small and the large extruder gear). It allows a very accurate adjustment of the hobbed teeth grip into the filament. At me it works that perfectly, that rather the large gear crashed than that the hobbed slips along the filament :). I used two 9mm bearings and one 8mm bearing.