WillowFlex & Bowden extruder - and it prints!

Although WollowFlex is a flexible filament, it can be printed amazingly well on 3D printers using a Bowden extruder.

My test was done on the neo from German RepRap. A very cheap device that delivers very acceptable results. The neo has a Bowden hose of over 70cm in length, with several sharp bends. So difficult conditions.


I retrofitted the neo with active cooling. I think every FDM printer should have active cooling. As long as you don't use ABS, you will improve the print quality many times over!

If you follow my tips, you will find yourself on devices with shorter and less twisted bowden hose, such as educate the Kossel even better results.

Retraction is important! Everything depends on the Retraciton!

You won't be able to avoid the right retraction settings for your device: Retract a lot and retract quickly. Then you can get the oosing under control. You have to retract so far that the spring travel of the filament in the tube is used up and then 2 mm further. I tried measuring, but unfortunately unsuccessfully.

If you retracted too far you will have problems with jamming filament because it will stick to the edges of the connections inside the extruder.

This part has served me well:


however, you do not need to try it until it looks good (it will never), but only until you have found the maximum withdrawal distance at which the filament is not jammed and the print runs without problems. On the neo that is 6.8mm.

Retracted quickly! 100mm / s is not a problem if you follow the next tip:

Pressure is important

Don't crush the filament! WillowFlex offers excellent grip for the feed wheel. Adjusts the counter pressure wheel gently. There is no setting option for the neo; therefore I had to replace the built-in spring with a weaker one. The built-in original spring is extremely generous even for PLA! If the pressure is too strong, WillowFlex deforms after two or three retractions over the same point and is no longer supported.

As I said, the material has good grip. You don't have to squeeze it.


Prints at a constant speed!

The print quality is very good if you print at a reasonably constant speed. I.e. inner and outer sheath (peremiter), and infill all at the same speed. So there is no jam and no loss of compression in the Bowden hose and the melt is conveyed beautifully evenly.

I have had good success with 30mm / s to 50mm / s. I may be able to drive even faster on other devices.

Active cooling: full power!

From the second layer you should cool what the fan gives. I also recommend the minimum print time per layer to 10 seconds. To step up.

Give it a try. It works! WillowFlex is a material with many great properties. It is wonderfully flexible and you can use the infill to set the hardness of your object. It can withstand temperatures from -18 to 110 ° C without changing its properties. It is compostable and it adheres to PLA for great composite prints.

This article is not necessarily finished. If you get further insights let me know. I will try it out and add it. So everyone can benefit from it.

Email: fd@3dk.berlin

My settings: Cura

Printer: neo from German RepRap
Slicer: Cura

Temperature nozzle: 180 ° C

Temperature print bed: 60-70 ° C or cold on tape or permanent print bed

Retraction: speed 100mm / s distance 6.8mm

Speeds: empty run 150mm / s; outer shell, inner shell, bottom layer, filling speed, top / bottom every 30mm / s

Switch on the fan: yes, always with 100% from 0.3mm height!

Minimum printing time per shift: 10s (Picachu's ears were unfortunately too small to get them clean :-( printed in double original size)

I wish you much success with WillowFlex on your printers.

See you, Florian