This is the makerbot spring-loaded extruder modded for Infitary Printer (even known as Alunar mini R100). I made this mod to match every element with the original Infitary Extruder pieces, so every component taken from the original extruder is suitable to be used with this project.
I made a spacer for spring hole, to calibrate the spring force on the filament, in my case two spacers are sufficient to exert a force on filament for a correct extrusion.
In the picture, some parts (such as the pieces Main and Cover) have been printed in ABS, but the configuration is referred to a PLA filament. If you follow the instruction, I'm pretty sure you can get perfect pieces.
Every note about printer configuration is reported in the configuration picture.