New Wade extruder for Skeleton 3D

After building Catastrophe's fantastic little Skeleton 3D printer , there was 1 thing about the printer that didn't work to my satisfaction: the extruder.
It works perfectly wel for PLA but for ABS it jammed regularly.
This is because ABS is both softer and more slippery and the extruder was designed and tested only for PLA by its designer.
I asked one of my best friends , and retired teacher in design with Inventor, to help redesign and draw in inventor a new extruder.This one should b