What are some of the challenges of working with a printer that has a bowden cable? A bowden cable machine is a machine that has the drive motor at one end but then the nozzle and the extruder at the other. Printers with bowden cables are very common. Most Ultimaker printers use this and a number of Ender printers use bowden cables. The reason they are used is because a bowden cable keeps your extruder head light and doesn’t cause vibration at the printer head as it moves around while printing. This means that these machines are good for high resolution, high surface quality, parts.
The problem with bowden cables is they aren’t good with very many materials. With bowden cables, you are pressing filament through a tube backwards. The machine pushes the filament from the front to the back while going through all the friction of the tube. Because of this, they're very tough to control and tune which is why they are only used by very heavily controlled machines that have really defined print profiles.
Knowing this, bowden cables can give great print quality if you've got the settings tuned appropriately. However there are things to be concerned about if you are tuning a machine or you're working with bowden cables.
1.) Retraction Legs
2.) Soft Materials
When printing with exceptionally soft materials like TPUs (thermoplastic polyurethane) you must be extra careful when working with bowden cables. Bowden cables are very difficult to work with because the filament material compresses inside the tube. Because it's rubber, the filament expands inside the tube and tends to stick to the inside of the tube. Even though PTFE tubes are very frictionless, they still have a lot of compression inside of the tube. The way to print TPU with bowden extruders is to go very slow. Think of it like a compressed spring. It needs time to compress and release otherwise you'll end up with inconsistent flow and jams.
3.) Abrasive Materials
If you have a bowden extruder machine those are the basic things to control. Remember to make sure that you're dealing with the extra retraction distance to take out the slack, if you're working with TPU go really slow to give it lots of time, and if you're working with abrasive materials make sure to replace the tube every once in a while. Be sure to check out our YouTube video on this topic on our YouTube Channel. Over there we have more tutorials and how-tos for 3D designers and makers of all levels.