MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
You have to stick the hobbed bolt inside extruder the other way around.http://reprap.org/wiki/File:ToyREP-61-Hobbet_Bolt_With_Gear.jpghttp://reprap.org/wiki/File:ToyREP-68-Installing_Hobbed_Bolt.jpghttp://reprap.org/wiki/File:ToyREP-70-Installing_Extruder.jpg
Pick the right gear for your hobbed bolt from thing files per the distance of groove to hex head. Use washers to align filament and the groove. The filament will lock the position so there is no need for nut on the other side of the extruder and you will avoid this kind of collision.