Idler for Direct Drive Extruder

A spring-loaded bearing idler for 1.75mm filament. It should be compatible with the Makerbot mk7 and the Makerbot mk7 Drive Gear, but I designed it for a spur gear from SDP-SI: S10T05M020S0505. It has clearance on the bearing side so you can print a mirrored idler and use it in a dual extrusion setup.

The overhead lever design was inspired by http://www.thingiverse.com/thing:15718 . That design has no filament guide which is required with a spur gear. The idler bearing also seems to conta