Extruder for Prusa Type Printer

This is a direct drive extruder for the block type nozzles. The difference here is that the filament path is as close to the hobbed gear as possible to keep the filament bending to a minimum.
It has positive grip through a spring tensioner on the bearing arm. I tried it on a printer that had a very sketchy setup. When the nozzle wasn't causing problems, the extruder worked great.

The combined print has the arm bearing set for the center of the filament path. Due to some slop in the print, I made another bearing arm with the bearing 1mm lower. This seemed to improve contact on the filament.

The bearing uses is a R188-ZZC .5" o.d., .25" i.d., .187" thick.
The spring is a C-510, .5" long, .25" i.d. cut nearly in half.
Use whatever bolt you have to fit. I used 1-1/2" 4-40.