Why belt Drive?
I designed this extruder to be belt drive for many reasons.
1 - Dependability
2 - No Lash
3 - Precision
4 - Price
Gear drive extruders at this point in time suffer from lash problems as well as dependability. So far people tend to use 3d printed gears or steppers with built in gearboxes. The 3d printed gears become a high wear item over time. The gearbox steppers have very high gear ratios as well as very high prices attached to them. Neither solves the slop problem.
The Modicum extruder...
First off I named it Modicum as it translates to small or petite. This extruder design is supposed to be as small as possible as well as strong as possible.
Here is my initial design.
As you notice on this shot, the shaft I am using is only 4mm. I ordered 5mm shafts and will be using them soon.