RepRap Pro Ormerod Spring-loaded extruder

After problems with inconsistent filament diameters in my RepRapPro Ormerod I made an extruder block that includes a spring for tensioning.

It uses a long 3mm screw, nut and a tension string on a long lever arm. I've implemented this one with great results - it handles variations in filament with ease.

This works well with variable filament diameters. Smooths out the action of roughly printed gears. Makes cleaning the hobbed insert a snap - Undo the bottom spring screw, flip the back up an