An extruder design based on the SeeMeCNC EZStruder. It constrains the filament from the drive gear all the way to the hotend so flexibles should work very well.

It uses SeeMeCNC's drive gear, but any 12mm OD drive gear should work if you line it up properly. The spring from the EZStruder is meant to be used for the arm. The bearing that attaches to the arm is a 608 and it gets fastened by an M4 bolt and washer combo. It is designed to use a PTC connector that E3d provides that allows the PTFE tube to go right up to the drive gear.

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Extruder, SeeMeCNC, RostockMAX, Orion, EZStruder