This is a modified spring loaded hinged version of the original V4 Filament Drive for the Makergear M2.
My original drive (printed in PETG) wore out (the springiness of the tension of the bottom of the drive) so I designed this hinged version to overcome it wearing out again. I also added the springs because I hate having to adjust the screw tension for different filaments. I also added two screws for the tension to hopefully get a move even tension on the bearing.
I used (2) M4x25 screws/nuts, some cut down springs from the hardware store (sorry no idea what rate they are), and a finish nail (4D maybe) for the hinge pin.
The fan mounting point on this is offset so if you run the stock fans you may have to add a longer bolt and spacer to use them. I do not run an extruder fans and I use a blower motor for a bed fan (because they are quiet) so my mounts are different than the stock version.
This is the blower motor I use (http://www.amazon.com/uxcell%C2%AE-Brushless-Sleeve-Bearing-Cooling-50mmx15mm/dp/B00W8W8LMM?ie)