Under certain circumstances, it can happen that the Bowden tube slides out of the feeder during printing. When this happens, the material continues to feed but will no longer extrude properly. Unfortunately, the printers have no means to detect this failure mode.
If this happens and it is not detected early, the material will coil up behind or inside the printer. This results in a failed print and possibly a clogged print core or nozzle, as material degrades in the hot end due to lack of extrusion.
Investigation and solution
Ultimaker is investigating the root cause and the solution for this problem. The Bowden tube can slide out, while the tube coupling collet and clamp clip remain in place in the feeder. This indicates insufficient clamping force on the Bowden tube. Hardware improvements are currently in development.
We have seen good results with using a thicker clamp clip on the feeders:
The clamp clip locks the tube coupling collet in place; the collet’s legs are pressed slightly inwards by the inside conical surface of the feeder. The blades of the collet now grip into the Bowden tube’s outer surface.
The thicker clamp clip increases the clamping force on the tube.
After further internal testing and validation, this thicker clamp clip will be released as the new standard part to use on all feeder assemblies. In the meantime, the STL file is made available. This can be downloaded at the bottom of this page.
Note: These clips are recommended to be used on the top of the feeder for any Ultimaker 3D printer type. We have also seen some cases whereby the Bowden tube comes out of the print head, and (on the Pro Bundle) whereby the Bowden tube slides out of the decoupler. The thicker clamp clip can also be installed in the print heads or at the top of the decoupler modules when issues are encountered.
The thicker clamp clips do not require complicated printing strategies and are simple to print. The following tips can help you to improve the results, though:
The clips can be printed with most Ultimaker materials. PLA, Tough PLA, or PETG would be good choices as they are easy to print.
Although the color of the clips won’t influence their function, it is recommended to print them in a different color than white. The printed clips look very similar to the default ones; printing them in a contrasting color will help to keep them apart and prevent mixups.
Use a 0.4 mm nozzle or smaller. The print core AA 0.4, or the 0.4 nozzle on an Ultimaker 2+ (Connect) can achieve sufficient detail for the clips. The 0.25 nozzle size may be used as well, but will increase print time.
Using a bigger nozzle size will reduce the accuracy of the clip.
A layer thickness of 0.1 mm or smaller is recommended. Do not use too thick layers, as this may affect the accuracy of the height of the printed model.
Tip: For Ultimaker S-line printers, the Engineering 0.1 profile can be selected for good results.
The only recommended change to the default profile is to turn off build plate adhesion. A skirt is sufficient for such small prints and removing the brim will be difficult. Apply a thin layer of glue to the build plate to ensure optimal adhesion.
Need further support?
If you have installed the thicker clamp clip(s), but you are still experiencing problems with the Bowden tube coming out of the feeder or decoupled, please contact support by submitting a ticket. Please share your printer type, where the problem occurred (for example: 'Feeder 2'), and include some photos.