Bowden tube gets pushed out during printing
Our bowden couplings can withstand a force of 14 kg for the 4 mm Pushfit connector and 22 kg for the 6 mm Pushfit connector under ideal conditions. If your bowden tube keeps getting pushed out it is not a problem with the extruder, the root cause of the problem originates from another source. Below we have listed the most common probable causes. It can originate from one of them or be a combination of several problems.
Important to know if the tube have been pushed out.
Very IMPORTANT! If the bowden tubes have been pushed out, you will need to cut off approximately 10 mm in order for the steel teeth of the bowden coupler to bite into a fresh PTFE surface.As the tube get damaged after repeated pushouts, failing to refresh the bite area will invariably result in more pushouts.
Bowden tube not properly inserted
If there is a movement during retractions the teeth in the coupler will eat itself into the PTFE and this will lead to a pushout sooner or later, therefore we recommend that this procedure is followed when connecting the PTFE tube.
- Remove the bowden clip.
- Grab the black collar with your nails.
- Pull the black collar upwards when at the same time push the PTFE tube hard into the extruder, make sure the PTFE tube is all the way into the housing.
- Try to jerk the PTFE tube out and in, if there is any movment repeat step 3.
- Place the bowden clip under the black collar.
Bowden tube diameter
For our 1.75 mm extruders the PTFE tube must not be smaller than 4.0 mm, imperial size 5/32″ is 3.96 mm nominal so it is too small in order to have an optimal grip in the pushfit.
With our extruders for 2.85/3.0 mm filament we recommend to use our PTFE tube that is 6.4 mm outside diameter and 3.18 mm inside diameter (1/4″x1/8″), this will give maximum gripping force of the tube and as an added bonus it will also reduce the hysteresis effect during retractions that will make it possible to use shorter retractions distances.
Tip! If your diameter is slightly too small you can use a lighter to heat up the end of the PTFE tube until it gets clear and then let it cool off, due to the memory effect from the extrusion process the diameter will increase some tens of a millimeter and will improve the grip. Make sure to do this in a well ventilated area since the fumes from PTFE is toxic.
Bowden tube not fully inserted
If the bowden tube is not fully inserted into the housing it can move that can lead to that the bowden gets pushed out, make sure the PTFE is seated all the way into the housing.
Bowden clip is not used
If the bowden clip is not used the bowden tube will move during retractions, this can give the bowden enough momentum to break out of the bowden connector. It is also bad for your retractions since a part of the retraction distance gets eaten up of the movment of the bowden tube. If you do not have any bowden clips you can download them from the links below.
|Bowden clip for 4 mm Pushfit||Bowden clip for 6 mm pushfit|
Our bowden adapters will let you connect a bowden tube to the bottom of the extruder, this way you can use the bottom port as the output port. When using it as an output port it is important to make sure that the PTFE tube extends through the bowden adapter as it otherwise will be a free space where the filament can buckle and create jams. The PTFE tube in below pictures are highlighted in blue color.
|X-section of QR 2.85/3.00||X-section of QR 1.75|