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With direct drive 3D printers becoming cheaper and more widely available, bowden tube setups are becoming a thing of the past. Despite the rise of direct drive extruders, Bowden tube 3D printers are still common.
A Bowden tube is a synthetic PTFE tube that guides filament from the extruder to the print head. Bowden tube 3D printers have a stepper motor mounted to the printer’s frame that feeds filament to the hot end.
PTFE tubes are essential for guiding the filament to the print end so that the filament doesn’t break, bend, or snap.
Direct drive 3D printers have the feeder motor mounted at the top of the print head. Direct drive machines don’t require a Bowden tube as they have a shorter distance between the nozzle and the extruder gears.
Pros and Cons of Bowden Tubes
Bowden tube 3D printers have specific advantages and disadvantages compared to direct drive systems. Here’s a list of their pros and cons:
Lighter Print Head: Separating the extruder from the print head reduces its weight. This can lead to faster movement, less inertia, and potentially higher printing speeds.
Improved Print Quality on Certain Prints: With less weight on the print head, there are fewer vibrations and more stable movement. Reducing vibration improves print quality, especially for prints with rapid or intricate movements.
Good for Large Printers: Bowden setups are often preferred in larger printers where a heavy print head could be problematic, allowing for more consistent movement across a larger build area.
Better Cooling: With more space around the print head due to the absence of the extruder motor, there is room for more effective cooling solutions, which can be beneficial for print quality.
Reduced Precision with Retraction: The distance between the extruder and the hot end can make retraction settings (pulling back the filament to prevent oozing) more difficult to calibrate, leading to stringing or blabbing on prints.
Not Ideal for Flexible Filaments: Bowden tubes can make printing with flexible filaments like TPU more challenging, as these materials can compress or buckle inside the tube.
Possible Increased Filament Drag: The filament has to travel a longer distance through the tube, which can create additional friction and resistance, affecting extrusion consistency.
Difficult Filament Loading and Unloading: Loading and unloading filament is more cumbersome than direct drive systems, as the filament must be threaded through the longer Bowden tube.
Types of Bowden Tubes
If your 3D printer uses a Bowden tube configuration, it likely comes with a standard plastic PTFE tube. The standard tubing is good enough for most PLA printing, but it won’t withstand the high temperatures of other filament types.
Capricorn tubes are a specialized type of PTFE (Teflon) tubing used in Bowden extruder setups for 3D printing. They offer several benefits over standard PTFE tubes, including:
Tighter Tolerances: Capricorn tubes offer extremely tight internal diameter tolerances. This precision reduces the play and slack for the filament inside the tube, leading to more consistent extrusion and improved print quality.
Enhanced Performance with Flexible Filaments: The tight tolerances are especially beneficial when printing with flexible filaments like TPU. These materials are prone to buckling within the tube, but the precision of Capricorn tubes minimizes this issue, making flexible filament printing more reliable.
Reduced Friction: Capricorn tubes have a slicker internal surface compared to standard PTFE tubes. This reduced friction allows for smoother filament feeding.
Durability: Capricorn tubes’ are more durable and less prone to wear and tear than standard PTFE tubes. This means less frequent replacement and better long-term performance.
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Overall, Capricorn tubes provide enhanced precision, reduced friction, and greater durability, making them an attractive upgrade for 3D printing enthusiasts and professionals looking to optimize their printing performance, particularly with challenging filaments or intricate print jobs.
Replacing a Bowden Tube (Step-by-Step Installation Guide)
Below is a step-by-step guide to replacing a Bowden tube on a 3D printer.
Power Off the Printer: Always start by turning off your 3D printer to ensure safety.
Remove the Old Bowden Tube: Most 3D printers use pneumatic couplers at both ends of the PTFE tube (near the extruder and the hotend). Press down on the ring of the coupler while gently pulling out the Bowden tube.
Measure and Cut the New Tube: If you’re replacing the tube with one of the same length, use the old tube as a guide to cut the new one. Otherwise, measure the required length according to your printer’s specifications. Ensure you have a straight cut at the end of the tube.
Install the New Tube:
Insert into Extruder End: Push the end of the new Bowden tube into the pneumatic coupler at the extruder end until it won’t go any further. It’s essential to ensure that the tube reaches all the way down.
Secure in Hotend End: Feed the other end of the tube through any necessary guides or supports and then into the coupler at the hotend. Again, make sure it is fully seated.
Reattach any Clips: If your printer uses clips to secure the tube in the couplers, reattach them now.
Check for Free Movement: Make sure the tube allows for free movement of the print head across its entire range. It shouldn’t be too tight or cause any strain on the couplers.
Test the Printer: Before starting a print, manually feed some filament through the new Bowden tube to ensure it moves smoothly. It’s a good idea to perform a test print to check that everything works correctly.
Now, you have successfully swapped out your Bowden tube.
Over time, you may notice that the tip in the hot end will begin to deteriorate (even the Capricorn Tube). To save money and extend your Bowden tube’s life, cut the tube back and reinstall it into the hot end.
A Bowden tube is a simple yet vital part of your FDM printer. It is responsible for delivering the filament string from the extruder motor to the Nozzle, significantly impacting retraction.
If not installed correctly, the Bowden tube can cause many headaches as it may be responsible for clogging, stringing, and other surface defects.
Marcello De Lio
Marcello co-founded 3D Print Mentor to share his love of 3D printing. Marcello used to own an online 3D printing company, where he sold unique designs and customized novelty gifts. After closing the business, Marcello’s new passion is 3D printing replica movie props and cosplay items.