This is an experimental extruder that uses an MK7 and no bearings or hobbed bolt. The design is not yet final, however i've been using it for a while now and it's doing a good job so far. The files include 2 big gears, top M5 has the M5 nut hole on the top of the gear and the bottom M5 has the hole on the bottom, both work fine, but the bottom M5 will give a bit more space between the X motor and the gears. When using this on a Smartrap, you need to use the long bowden guide found at https://github.com/smartfriendz/smartrap/blob/master/stl/dev/V0.4.7/bowden_guide.stl , don't forget to calibrate your e-steps, i currently use M92 E528 in my custom startup gcode. The extra parts needed are :