How to Choose Between a Bowden and Direct Extruder for 3D Printing

In the 3D printing landscape, the extruder configuration you choose can make all the difference between a successful, flawless print and a frustrating trial-and-error process. FDM 3D printing extruders come in a variety of shapes and forms, but despite the intricate differences of each extruder, they all cater to either one of two types of setup. Bowden and the direct drive extruders are the two distinct powerhouses, each armed with unique advantages and challenges. But how to know which one to choose? To unravel the intricacies of these extruder types, we took a closer look at the performance of both in terms of print quality, speed, versatility, and more.

Before going into the differences, it is important to look at what exactly an extruder is. An extruder is a vital component of the FDM (Fused Deposition Modeling) 3D printing process. Not to be confused with the nozzle, it serves as the mechanism responsible for precisely feeding filament material into the hot-end of a 3D printer where it is then melted and deposited layer by layer to create a three-dimensional object. The extruder is tasked with maintaining consistent filament flow, controlling the rate of extrusion, and ensuring accurate placement of the molten material onto the print bed. Its role in the printing process makes the choice of extruder type a critical decision, as it directly impacts factors such as print quality, speed, material compatibility, and the overall capabilities of the 3D printing system.

Photo credits: Sculpteo

Bowden vs. Direct Extruder: What to Know

But what exactly is the difference between the two? A Bowden extruder is characterized by its separation of the extruder motor from the hot-end assembly. A PTFE tube (also known as a Bowden tube) connects the components, allowing for reduced moving mass on the carriage and enabling faster movements during printing. This configuration is favored by those aiming for smoother, faster prints. The Bowden setup excels in minimizing vibrations, which is especially advantageous for printing intricate and delicate models. That’s because there is less mass to suddenly move. Since the force of acceleration is equal to mass times speed, it is easier to quickly accelerate and decelerate a lighter object. Also, the lighter the object, the less momentum (kinetic energy) it builds up. However, the increased distance between the extruder motor and the hot-end can result in challenges with flexible filaments, as they tend to buckle inside the tube, affecting extrusion consistency. Part of this problem is also the friction induced by the PTFE tube, or Bowden tube.