What Is Bowden Tubing?

We may have heard about Bowden tubes, but do we really know what they are? and how they are different from other types of extruders? This article would provide all the necessary information about Bowden tubes that you need. Keep reading to learn more.

In any FDM 3D printer, the extruder is a critical component where the filament is melted and pushed out. A stepper motor and a hot end make up an extruder. When the filament is gripped by the stepper motor and sent to the hot end, the plastic is then melted onto the bed. Extruders are divided into two categories: Direct drive and Bowden extruders.

On a direct drive extruder, the stepper motor is built within the print head, allowing the filament to be pushed directly into the hot end. As the print head moves along the x-axis, it must bear the weight of the stepper motor.

The motor of the Bowden extruder is on the frame and the feeding mechanism on a Bowden design is frequently located far from the extruder's hot end. This is where the Bowden tube comes in, the motor feeds the filament to the print head via a Bowden tube.

Bowden extruders are filament feeding mechanisms that push filament via a long and flexible PTFE (Teflon) plastic tube to the hot end in various FDM 3d printers. The tube protects the plastic from breaking or being stretched as a result of frequent movement by guiding the filament from the fixed motor to the moving hot end.

For us to get the best effectiveness out of using Bowden tubes, we have to learn about the benefits and drawbacks that come with their nature.

How Bowden Tube Affects Your Print Quality

Here's a rundown of how Bowden tubes affect the quality of your printed 3D objects.

Pros

• Printing speed is increased:  Bowden tubes provide less strain on the axis motors because the stepper motor's weight isn't on the print head. To reach a high speed, less force and torque is required.
• Increased precision: Bowden extruders allow 3D printers to move with less acceleration and jerk since the print heads are lighter as opposed to direct drives, this implies they can achieve more exact movement, resulting in fewer irregularities in layers.

Cons

• There's more leaking and stringiness:  As a result of the Bowden tube being so lengthy and the stepper motor so far away from the hot end, extrusion and retraction are slightly delayed. This causes increased stringiness, which is especially noticeable on overhangs. However, by increasing the retraction distance and pace, this is generally easily remedied.

Filaments and Troubleshooting

With Bowden tubes, it can be challenging to print using flexible and rubber-like filaments. The plastic readily bends and becomes caught in the tube since these filaments aren't stiff. But all hope is not lost. You can still print with flexibles if you double-check the filament brand and 3D printer model, and prepare to experiment with print settings.

In general, troubleshooting with a Bowden tube is more difficult. If a filament becomes clogged, it must be retracted, the whole length of the tube or the tube and extruder must be dismantled so that it may be cut. You also waste more filament because you constantly need at least a tube's worth of plastic to print anything at all.

Replacing the Bowden Tubes?

Forwarding filament that has been poorly chopped or ground down through the Bowden tube may scratch or harm the tube's inside. If this happens, the filament will no longer be able to flow smoothly to the print head. Under extrusion or other print quality, concerns may arise as a result of this.

The tube coupling collet can wear out if you remove the Bowden tube too many times as the coupling collet will no longer have a tight grip on the Bowden tube if this happens. This would cause the tube to move up and down during prints in this instance, lowering the print quality.

The Bowden tubes must be changed if they are irreversibly damaged. It is advised that the Bowden tubes be replaced once a year to preserve the optimal print quality.

How to replace the Bowden tube

Uncoupling

• Navigate to Material/PrintCore > Material [x] > Unload. After that, switch the printer off.
• Place the print head in the upper-right corner.
• Remove the clamp clips from the tube coupling collets at the print head and feeders with your fingernail.
• Pull the Bowden tube upwards and out of the print head while pressing down on the tube coupling collet in the print head. Follow the same procedure for the feeder.
• To completely remove the Bowden tube from the extruder, detach the four cable clips from the Bowden tube.

Reassembly

1. Take a look at the two sides of the new Bowden tube. The feeder should be placed into the drilled side. This makes it easy for the filament to enter the Bowden tube. The print head should be inserted from the flat side.
2. By pulling down on the tube coupling collet in the feeder and pushing the Bowden tube all the way in, the Bowden tube will be inserted into the feeder. Secure the tube with the clamp clip.
3. Insert the Bowden tube into the print head by pulling down on the tube coupling collet in the print head and pushing the Bowden tube all the way in,  Also secure the tube with the clamp clip.
4. Click the header cable clamps into the Bowden tube when replacing the Bowden tube from the extruder. Distribute the clips evenly around the Bowden tube.

Cleaning the Bowden tube

Fine strands of filament or small particles of material in the Bowden tubes can cause friction and obstruct the filament's smooth movement which would eventually lead to under-extrusion and failure to print properly. It is ideal to clean the Bowden tubes at least once a month, or whenever you have a filament grinding problem. The Bowden tubes must first be removed from the printer before they can be cleaned.

How to Clean the Bowden tube

1. Cut a little piece of sponge or roll a piece of tissue into a ball.
2. Insert this into the Bowden tube's feeder end and pull it all the way through using a length of the filament.
3.  Replace the tube in the printer, paying attention to the right sides of the tube in the printer/print head. (The print head side of the tube is slightly wedge-shaped on the outside.)

Importance of Bowden tubing

When using a Bowden drive, the print head is smaller and the extruder motor is fixed to the frame of the printer, hence the need for a Bowden tube. The Bowden tube helps to prevent the filament from twisting and bending. This tubing is required to force and guide the filament into the hot end. If the Bowden tube breaks or unscrews, the hot end will stop extruding and the filament will tangle over the frame.

Asides from guiding the filament into the hot end, the Bowden tubes are also useful to prevent the filament from getting contaminated.

Advantages of Bowden Tubing

1. Bowden-type extruders or Bowden tubes are easier to change since they are located outside the print head.
2. Bowden tubes are less likely to tangle the filament as it unwinds from the spool.
3. The extrusion carriage does not have to hold a stepper motor, this makes it lighter.
4. The Bowden extruder enables faster changes in the print head movement direction, increased print speed, improved accuracy, and reduced artifacts or ghosting along the X and Y axes.

Disadvantages of Bowden Tubing

1. One of the disadvantages of the Bowden extruder is having to overcome greater friction than direct drive extruders since they force filament via a long and curved tube. The tube is composed of PTFE, which has a low coefficient of friction, to help minimize these friction forces.
2. Because the filament flexes inside the tube and clogs the machine, flexible filaments do not print well when using the Bowden tube or extruder.
3. Another disadvantage is that the feeding distance is rather lengthy, resulting in high resistance, requiring a higher torque stepping motor for extrusion.

Conclusion

As it is our desire for you to be able to produce 3D printed models using the Bowden type extruders and Bowden tubing without any unnecessary hassle, we do hope that this article has helped to ease your worries by providing information on all there is to know about Bowden tubing.

These include the proper techniques for cleaning, dismantling, and reassembling your Bowden tubes as well as any other important concept of Bow