Oct 31, 2018

Direct vs Bowden Extruder – 3D Printing Technology Shootout

We've all heard of printers with direct and bowden extruder setups. But what's the difference, and which is better? We explore the differences, looking at the pros and cons of both direct and bowden extruders.

Direct vs Bowden Extruder Extrusion 101

Direct vs Bowden extrusion. Source: Craftunique

Most filament 3D printers use either direct or bowden extrusion. Both set-ups use an extruder to push filament through a heated nozzle, either directly or through a bowden tube. Though similar, these extruder formats have major differences. Let’s begin exploring the definitions, pros, and cons of these two systems. 

Direct vs Bowden Extruder Direct Extrusion

A direct extruder. Source: Filastruder

Direct extrusion is a method of extrusion by which the extruder pushes the filament directly into the nozzle. This method is helpful for many reasons, but it also has some downsides. Let’s take a look.

Pros

  • Better Extrusion: Since a direct extruder is mounted to the print head, the motor can easily push filament through the nozzle, allowing for better extrusion.
  • Faster Retraction: Because the extruder is close to the nozzle, the direct extruder can quickly retract filament.
  • Less Powerful Motor: Due to the short distance between the extruder and nozzle, less torque from the motor is required to push filament.
  • Wider Range of Filaments: A direct extruder is compatible with a wide range of filaments. Even with flexible and abrasive materials, direct extrusion allows for reliable printing.

Cons

  • Burdened Movements: With the extruder mounted to the print head, weight is obviously added. This extra weight adds speed constraints, causing more wobble and possibly a loss of accuracy in the X and Y axes.

Direct vs Bowden Extruder Bowden Extrusion

A Bowden extruder. Source: Thingiverse

Unlike a direct extrusion machine, a Bowden extruder is mounted on the printer’s frame. It pushes and pulls filament through a long PTFE Bowden tube and into the hot end. This system also has pros and cons.

Pros

  • Cleaner Movements: Since a Bowden extruder is mounted on the printer’s frame rather than on the print head, much less weight is on the carriage. Less weight means faster, quieter, and higher quality prints.
  • Larger Build Volume: A Bowden extruder allows for a smaller print head carriage, which, in turn, allows for increased build volume.
  • Compact Size: Bowden extruders are typically more compact, taking up less space than a normal direct extruder. 

Cons

  • More Powerful Motor: Because a Bowden extruder is pushing and pulling filament through a long tube, a certain amount of friction exists between the two. This friction calls for more torque to control filament.
  • Slower Response Time: More friction in the Bowden tube also translates to slow response time. Bowden extruders require longer and faster retraction to avoid stringing.
  • Smaller Range of Materials: Some flexible and abrasive filaments can easily bind or wear in Bowden tubes. 

Direct vs Bowden Extruder Verdict

Source: Thetruthaboutguns

So, which system is better? It depends. Before you decide which extrusion format to use for your printer, you should consider some important factors.

The first is frame stability. Delta printers, for example, cannot support a direct extruder. If, however, your Cartesian or CoreXY printer has a sturdy frame, printing with a direct extruder should be no problem.

Speed is also a deciding factor. If your priority is fast, precise printing, with standard materials, Bowden extrusion will be more satisfactory

Lastly, you should consider the materials you would like to print. If you’re interested in flexible or abrasive filaments, a direct extrusion system is likely the one for you. 

Good luck finding your perfect extruder! Happy printing!

License: The text of "Direct vs Bowden Extruder – 3D Printing Technology Shootout" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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