Extruder Drives You have so many options for driving filament down into a hot-end and that itself would really require a separate article. At the end of this I sum up the results but I have always found a geared extruder to be the most suitable for most of the printing I have done over the years. I just wanted to state here that I have tested lots of different types, and made many of my own, both direct drive and geared in one way or another over the last few years. Many different drive systems are in use for extruders.
After testing and using every different type I could get my hands on, I come back to the standard hobbed M8 bolt and a V groove 608ZZ bearing for the idler as my drive method of choice in most machines. Hobbed bolt
Example Direct drive extruder systems, very simple to assemble and service, but do tend to have limited torque to drive the filament and depending on the pinch system can be more prone to jamming or skipping lesser quality filament. Almost all apart from the Kraken testing used a geared drive extruder. for the Kraken you can use gearing but I found a standard Nema 17 with a direct pinch-wheel worked perfectly even at fast extruding speed.
Direct drive extruder gears