Glossary · Design

3D printing

Bowden

The drive for the plastic strand sits on the frame, and the strand runs through a tube to the print head. This makes soft materials harder to print.

Explained in more detail

The extruder is mounted on the frame and pushes the filament through a PTFE tube (often 30 to 60 cm) to the hotend. The print head becomes lighter, but the filament can buckle in the tube. Consequences: longer retraction (often 4 to 7 mm), more tendency to stringing and difficulties with soft TPU. On new devices it is mainly still common on small entry-level printers.

Where does the term come from?

Named after the Bowden cable, a cable in a sheath, as found on bicycle brakes, for example. It goes back to Ernest Monnington Bowden, who had it patented in the late 19th century. On the printer, the filament runs through the sheath instead of the cable.

In practice

• Typical retraction: 4 to 7 mm at 30 to 50 mm/s. Test the right value with a retraction tower.
• The PTFE tube must sit firmly in both fittings. A gap between tube and nozzle leads to clogs.
• Always cut the tube straight. Angled cuts leave gaps in which filament builds up.
• Frayed, discoloured or widened tube ends are best replaced. PTFE tube is an inexpensive wearing part.

Not to be confused

A PTFE tube between the spool and the print head does not make a printer a Bowden system. What matters is whether the drive sits on the frame or on the print head.

Frequently asked questions

How do I set retraction on a Bowden setup?

Start at about 5 mm and 40 mm/s and print a retraction test. Increase in steps of 0.5 to 1 mm until no strings appear. More than necessary can clog the nozzle.

Can you print TPU with a Bowden?

Harder TPU grades often work at low speed and short retraction. Soft TPU buckles in the tube and jams, so direct drive is the safer choice.