Getting Started: A Basic 3D Printer Explanation

This post is to de-mystify the basic operation of 3D printers for for those just getting started. The diagram below presents a functional exploded view of the filament path: 

1. The filament goes into the extruder, which has toothed gears to push the filament forward into the heat break. 
2. The heat break has a hot side and a cool side. The cool side of the heat break is embedded into the heat sink. 
3. A fan blows across the fins of the heat sink to help keep it cool. 
4. The hot side of the heat break goes into the heating block. 
5. The hot part of the heat break meets up with the nozzle, fitting tightly against it. This is where the filament is melted and pushed through the nozzle. 

In a setup where the extruder is mounted on the frame of the printer (known as a Bowden setup), there is a lot more distance between the extruder and the heat break (shown below). 

In order for it to work, the filament is fed through a PTFE ("Teflon") tube. It's like pushing water uphill: without a hose, it will never happen. However, the hose directs the water, making it possible. 

The problem with a Bowden setup is that there is elasticity and play in the filament and the tube, making it much harder to manage the filament precisely.  By contrast, with a direct drive setup there is almost no distance between the extruder and heat break, eliminating almost all of the play found in the Bowden setup. This allows a potential better print quality. 

This has a practical application for me: I'm upgrading an older printer I have from a Bowden setup to a direct drive in order to improve print quality. 

I hope this helps folks understand the basics.