Nowadays, there are two methods of extrusion typically found on desktop 3d printer from the market. For filament-based extrusion 3d printer,it is vital to ensure delivering filament to the hot end for the deposition on the build plate reliably.
We have all heard of printers with direct and Bowden extruder setups, but which one is better, and what is the difference between them? In this article, we are going to discover the pros and cons of both direct and Bowden extruders.
Direct Drive Extruder
As the word "direct" describes, the filament is directly inserted into the hot end, where it softens and emerges from nozzle in a precise extrusion line. A gear and wheel tightly grip the filament, the gear is rotated by a stepper motor, driving the filament downward on a short journey to the hot end.
- The control of the filament amount is more accurate and retraction is more precisely and quickly.
- The torque requirement of the extrusion stepping motor is relatively low.
- A direct extruder is compatible with a wide range of filaments. It supports multi-types of filament such as PLA, TPU, ABS, Wood, Cooper etc.
- As the hot end of nozzle, extruder, stepping motor, heat dissipation fan are integrated, so it won't be convenient to disassemble, assemble and maintain.
- This extra weight that attached to the print head will add speed constraints, causing more wobble and possibly a loss of accuracy in the X and Y axes.
The other style of extruder is known as the “Bowden” approach. The extruder and stepping motor usually installed on the shell of the machine, it pushes and pulls filament through a long PTFE Bowden tube and into the hot end.
- The Print head has advantage of light weighted, that means inertia will be smaller that results in more accurate moving and positioning, and Less weight means faster and quieter prints.
- The extruder and nozzle is separated, so the maintenance will be much easier.
- Bowden extruders are typically more compact, taking up less space than a normal direct extruder.
- The stepping motor responsible for extrusion is required to have greater torque because of its long pushing distance and high resistance.
- The extruder and the print head need to be connected with a Teflon tube and a pneumatic joint, more prone to failure with respect to direct drive extrusion.
- The filament and Teflon pipes have some elasticity, and the general pneumatic joints also have a certain moving space, so the requirement of pumping distance and speed are greater, which is not as good as the precision of direct drive extrusion.
- More friction in the Bowden tube also translates to slow response time. Bowden extruders require longer and faster retraction to avoid stringing.
- A relatively smaller range of material, some flexible and abrasive filaments can easily bind or wear in Bowden tubes.
So, Which one is best? Different answer for different people, it depends on your demands.
We’d recommend a direct extruder for most people, while a Bowden approach might be more useful to those with experience and time to tune their machine.