Jan 3, 2019

Bowden Tube – All You Need to Know

You may have heard of Bowden tubes, but what are they really? How are they different from other extruders, and which should you choose? Find out in this guide to Bowden tubes.

What Is a Bowden Tube?

Bowden on left, direct drive on the right. Source: CraftUnique

The extruder, where filament is melted and pushed out, is a key component in any FDM 3D printer. Extruders consist of a stepper motor and a hot end. The stepper motor grips the filament and feeds it to the hot end, which melts the plastic onto the bed. There are two main types of extruders: direct and Bowden.

A direct drive extruder has the stepper motor on the print head itself, so filament gets pushed directly into the hot end. This means the print head has to carry the weight of the stepper motor as it moves along the x-axis.

The Bowden extruder has the motor on the frame, far away from the print head. This is where the Bowden tube comes in. The motor feeds the filament through a Bowden tube (usually made of PTFE plastic) to the print head. The tube guides the filament from the fixed motor to the moving hot end, protecting the plastic from snapping or being stretched by constant movement.

Naturally, Bowden tubes have distinct advantages and disadvantages. Read on to learn more!

Print Quality

The Creality CR-10, one of the more popular Bowden extruder 3D printers. Source: Rimstar

Here’s an overview of how Bowden tubes affect the print quality of your 3D models.

Pros

  • Faster print speed. Since the weight of the stepper motor is not on the print head, Bowden tubes have less strain on the axis motors. This means less force and torque is needed to reach a high speed. 
  • Higher accuracy. Since print heads are lighter with Bowden extruders, 3D printers can move with less acceleration and jerk. This means they can achieve more precise movement, so there are fewer inconsistencies in layers compared to direct drives.

Cons

  • More oozing and stringiness. Extrusion and retraction are slightly delayed since the Bowden tube is so long and the stepper motor is far from the hot end. This leads to more stringiness, especially for overhangs. However, this is usually easily fixed by raising the retraction distance and rate.

Filaments & Troubleshooting

Replacing a Bowden tube. Source: Ultimaker

Flexible and rubber-like filaments can be difficult to print with Bowden tubes. Since these filaments aren’t rigid, the plastic easily bends and gets trapped in the tube.

Not all hope is lost, though. You can still print with flexibles — just check the filament brand and specific 3D printer, and be ready to play around with print settings.

In general, troubleshooting can be harder with a Bowden tube. If a filament gets clogged, you have to retract it the whole length of the tube or dismantle the tube and extruder so you can cut it. You also tend to waste more filament, since you always need to have at least a tube’s length worth of plastic to print at all. 

Which to Choose?

Either way, both printers should serve you well! Source: All3DP, Ultimaker

Ultimately, there’s no clear-cut winner between Bowden and direct drive printers.

For most, in fact, the difference between them won’t matter at all. The quality of a 3D printer depends on many more factors than just its extruder design, and the best printers will account for any of the weaknesses mentioned above.

That being said, we hope these few points will help you:

  • Pick a Bowden extruder if you value higher speed and accuracy and aren’t planning to print much with flexible filament.
  • Pick a direct drive extruder if you don’t mind trading speed for ease of mind when printing with a wide range of materials.

License: The text of "Bowden Tube – All You Need to Know" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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