Extruder Upgrades

I purchased a QU-BD extruder and I have found a very useful combination of parts to make it work extremely reliably. This is an upgrade on my last design "Very compact MK7 Upgrade" (http://www.thingiverse.com/thing:34757)

I am using the stock QU-BD extruder with the following changes.

1) I replaced the set screw that presses on the filament with a Ball-nose Spring Plunger from Mcmaster.com (3408A98) This allows a tight press on the filament with springloaded nose to compensate for inconsis