I really like the design of the belted extruder v4. But since I was too impatient to order an aluminium gear, I printed one.
The M8 hobbed bolt is simply inserted pressfit and therefore fits extremely tight and has no play. In the 2nd iteration I added a knob so that I can move the extruder by hand.
Another big advantage is that you can easily use the hobbed bolt as it is. You don't have to saw anything off or something like that. You only need two washers.
I also printed a small washer to get the right distance and let the ball bearing run freely.
I modified the the Gear from Naralex BallMill and compined it with the Extruder Knob from lonewolf78. Thank you both for your Designs! I am very satisfied with the result and think it can be seen :)