Extruders 

Types of extruders: Direct

In the direct extruder, as its name suggests, the filament runs directly from the cog of the extruder to the HotEnd. There are even systems in which these two parts are together, as in the Titan Aero.

The direct extruders allow the printing of rigid and flexible materials (1.75 mm and 2.85 mm) regardless of the composition of the filament. Another advantage is that they require low retraction lengths, reducing printing time and increasing the extruder motor life. Its main drawback is the inertias produced in the axis of the printer in which the extruder moves, caused by the weight and unbalance of the center of mass with respect to the axis. Another drawback can appear in closed printers and with a tempered chamber that can reach temperatures in the extruder motor that affect the performance of operation.

Types of extruders: Bowden

In the Bowden extruders, on the contrary that the direct extruders, the union with the HotEnd is through a PTFE tube through which the filament passes.

These extruders have low inertias in the axis of displacement of the HotEnd. The Bowden system, since the extruder and the extruder motor are anchored to the chassis of the 3D printer, greatly reduce the inertias in the movement to make the impression. This makes it possible to produce very fast prints and at the same time of high quality. Its main disadvantage is the great difficulty to print flexible filaments (TPE) of diameter 1.75 mm. This is due to the fact that being a flexible filament it is not possible to keep the pressure in the filament constant along the Bowden PTFE tube until the HotEnd, since it flexes the filament. In Bowden systems of 2.85 mm however it is possible to print the flexible filaments at low speed.