When buying an FDM 3D printer, one of the things to decide is whether you want a direct drive or Bowden extruder.
While both setups accomplish the same thing and work in a similar way, the differences between the two are subject to hot debates.
The main direct drive vs. Bowden extruder difference is the way they feed filament. Direct drive extruders are mounted on the print head and push the filament directly into the hot end; hence, their name. Bowden extruders are mounted on the printer frame and feed the filament through a PTFE tube.
Each setup comes with its own advantages and drawbacks.
Direct drive extruders equip popular printers like Prusa i3 MK3S+, the Anycubic Kobra, and the Ender 3 S1. Bowden extruders are found on all Ender 3 printers except the S1, Prusa Mini+, and Elegoo Neptune 2S.
7 Key Differences Between Direct Drive and Bowden Extruder
Direct drive and Bowden extruders push filament through the hot end in a slightly different way.
This creates differences that go from printer design and filament path to print quality and versatility.
1. Printer Design
The main difference between Bowden and direct drive extruders is their location on the printer, which affects the entire printer design.
Direct drive extruders are mounted on the print head, whereas Bowden extruders are mounted on the printer’s frame.
Due to their location right on top of the hot end, direct drive extruders add lots of bulk to the printer design. The hot end assembly is large and heavy, and often makes it difficult for the arm to move around.
Bowden extruders don’t add any bulk to the hot end, maintaining the overall design of the printer more compact. However, these printers have an extra component – a PTFE tube through which the extruder pushes the filament into the hot end.
This means an extra part to maintain and potentially replace. It may also mean more issues during printing. For instance, clogs in the Bowden tube can be responsible for the printer stopping extrusion mid-print or inconsistent extrusion.
2. Filament Path
Due to the different location of each extruder type, the filament path is also fundamentally different.
In direct drive setups, the filament goes into the extruder and then is pushed directly into the hot end. This very short path from extruder to the hot end makes direct drive extruders perfect for flexible materials like TPE or TPU.
Bowden extruders sit on the frame and have to push the filament into the hot end through a tube. The long path can negatively affect the homogeneity of the material to be printed, especially when working with flexible filaments.
3. Filament Compatibility
Because of the filament path, direct drive is the best option if your main purpose is printing with flexible filaments. This extruder type makes it easier to feed these materials without worrying about kinks or knotting.
Bowden extruders are a better choice for more rigid filaments like ABS and PLA.
You should also keep in mind that just because direct drive is better for flexible materials, it doesn’t mean that you can’t print TPU or TPE on an Ender 3 (other than the S1 model). You can, but to achieve satisfactory results, you should:
- Set the retraction at least 5 mm to prevent unnecessary oozing
- Select a PTFE tube with a tight tolerance to prevent kinks
- Use a hobbed bolt with a deeper profile to increase grip around the flexible filament and ensure constant feeding
4. Printing Speed
Direct drive extruders sit right on top of the hot end. Bowden extruders sit on the printer’s frame, and feed the filament through a tube. The longer path might lead you to believe that they need more printing time. However, the opposite is true.
Bowden extruders are actually faster than direct drive, because the extruder’s weight is distributed on the frame rather than weighing on the hot end. In fact, the heft added by the direct drive extruder to the hot end translates into a slower printing process and more vibrations.
Vibrations typically impact the print in a negative way, causing ridges and other surface defects.
5. Print Quality
Bowden extruders often take the hit as the least performing of the two types just because they aren’t that great with flexible filament. In reality, they often produce cleaner prints than direct drive extruders due to the vibrations mentioned above.
The placement of the extruder on the frame also gives the printing arm room to move around without fighting around extra weight. Due to the extra weight added by direct drive extruders, the printhead has to work harder during printing and could cause the filament to drag. This inevitably leads to less-than-perfect results.
Direct drive extruders win in terms of versatility. They are suitable for a wider range of filaments, including rigid, flexible, and even abrasive. In fact, Bowden drive printers can’t use abrasive filaments, since these will wear out the tube’s interior.
If you don’t ever plan on printing with flexible or abrasive materials, however, the Bowden extruder provides faster and more accurate results, allowing you to print a wider range of objects. Hence, which of the two is more versatile largely depends on your purpose.
7. Extruder Upgrade
Lastly, you must consider maintenance and replacement when comparing Bowden vs. direct drive extruders.
Due to the former’s placement on the printer’s frame, Bowden extruders are easier to access and replace. They do, however, throw more maintenance into the mix due to the PTFE tube.
That’s not to say that direct drive extruders are easy to maintain. Its placement on top of the print head can make it hard to access certain parts. These extruders are also more difficult to remove and replace.
Pros and Cons of Direct Drive Extrusion
Direct drive extruders are often considered better than the Bowden type. But is that right? Let’s have an in-depth look at its pros and cons.
- Reliable extrusion: In direct drive setups, the extruder is located right on top of the hot end. The filament travels a short distance from extruder to the printhead, which cuts down the risk of extrusion-related problems such as kinks or knots.
- Better retraction: Another advantage related to the extruder’s position is the more efficient retraction. There is less back-and-forth of the filament during non-extrusion movements, reducing the risk of filament stripping. An effortless retraction also means less burden on the motor.
- Less motor power required for feeding: Speaking of the motor, direct drive extruders also require less power for pushing the filament through the hot end. Once again, this means less of a strain on the part and an increased motor lifespan.
- Wider range of filaments: As mentioned, direct drive extruders are compatible with all filament types. Perhaps the greatest advantage is the possibility to print abrasive filaments, which don’t pair well with Bowden tubes. Printing flexible materials is also more straightforward.
- Fewer parts to maintain: an advantage related to the extruder’s configuration is the lack of a tube. Hence, there are zero chances of clogs in any other parts of the printer other than the nozzle. While a direct drive extruder cuts down maintenance, it doesn’t mean the process is straightforward, though.
- Reduced printing speed: The first drawback derived from the extruder’s placement is the reduced printing speed due to the extra weight that presses on the printhead. The arm will generally move slower compared to Bowden extruders.
- More motor power required for printhead movements: Another disadvantage related to the first one is that the extra weight on the printhead requires more power for arm movements. Hence, this kind of cancels the less motor power for feeding advantage.
- Complex maintenance: As mentioned, direct drive extruders have fewer parts, but they are more complex to maintain due to their placement. Parts are often hard to access, meaning that you might have to take apart the entire printhead.
- More wobble and possible loss of accuracy: Extra weight on the hot end means more fatigue during arm movements. This can easily lead to loose screws and consequent wobbling and loss of accuracy.
Pros and Cons of Bowden Extrusion
While Bowden extruders are often frowned upon, they could be your best bet if you’re typically printing with rigid materials like ABS or PLA.
- Cleaner movements: Unlike direct drive extruders, Bowden extruders add no weight to the printhead. This translates into cleaner movements, increased printing precision, and increased accuracy. As long as the printer is calibrated correctly for the material you’re using, you can expect quality results regardless of your experience with 3D printing.
- Increased printing speed: Another advantage related to the lack of weight is the faster, more fluid movement of the printhead. Bowden printers can cut off the time needed to create an object, helping you save on energy.
- Larger build volume: Since the extruder adds no bulk to the printhead, Bowden setups usually allow for an increased build volume. This means that you can print larger objects.
- Easier maintenance: Thanks to its placement on the printer’s frame, a Bowden extruder is a lot easier to access than the direct drive type. It also produces less vibrations and loose fasteners are a rare occurrence.
- Easier replacement: Not only are Bowden extruders easier to maintain, they are also easier to replace. You won’t have to disassemble any other components, making the process more straightforward.
- Slower response time: While Bowden extruders are faster, they have a slower response time in both feeding and retraction. Besides the fact that this setup requires more calibration, the back-and-forth movement can lead to filament stripping and inconsistent extrusion.
- Material complications: The diameter of the Bowden tube and the type of filament you’re using can have a negative impact on extrusion. If the filament diameter is too small, the material can kink inside the PTFE tube. If the diameter is too large, it can lead to clogging or inconsistent extrusion.
- More power for filament feeding: As mentioned, Bowden extruders require less power for arm movement. However, they need more power for filament feeding, as they have to push the material for a longer distance.
- Smaller range of compatible filaments: Bowden extruders are only truly compatible with rigid, non-abrasive filaments. They can work with flexible filaments too, but require lots of calibration for good results.
Which Is Better: Direct Drive Or Bowden Extruder?
Choosing between direct drive and Bowden extruders largely comes down to your needs. Do you want fast printing speeds and increased accuracy? The Bowden extruder could be right for you. Do you want to print flexible or abrasive filaments? Go for a direct drive extruder.
Both types have pros and cons, and as long as you know their advantages and limitations and match them to your needs, both extruders can provide good results.