Filament entanglement usually refers to the entanglement of the filament on the spool, resulting in the extruder being unable to pull the filament during the printing process and thus stopping the extrusion. Usually in this case, the filament detection sensor of the tool head is still triggered, it cannot trigger the filament-run-out reminder, which will cause the phenomenon of "air printing" during the printing. The Bambu A1 series is equipped with a filament tangle monitoring module to deal with this situation. When the filament is tangled, due to excessive feeding resistance, the corresponding sensor will be triggered, and the printer will automatically pause printing and pop up a reminder of filament entanglement. Customers can re-arrange the filament on the spool and continue printing. Avoid "air printing".
The tangle monitoring module is located above the tool head and consists of a filament Hub and feeding bracket. The filament Hub connects four PTFE tubes. The feeding bracket is connected to a Hall sensor on the side, and there's a spring inside. The lower part of the filament hub also has a magnet. After the filament Hub and the feeding bracket are assembled together, the magnet is like a slider that can move up and down, so as to form a tangle monitoring module. It mainly consists of a spring + slider (with magnet)+ detection sensor.
When the feed resistance is too high, the filament inside the PTFE tube is difficult to feed, and the extruder is still extruding the filament. Therefore, the extruder will consume the filament inside the tangle detection module, the spring inside it will be compressed, and the slider magnet will also be closer to the Hall sensor. By detecting the position of the slider through sensors, the feed resistance from the toolhead outside can be calculated. In addition, the spring also provides a buffering effect, so that there is still enough buffered filament for the extruder to consume when excessive feed resistance is detected, avoiding printing defects caused by "air printing".
In addition, the operation of the tangle detection system also relies on the PTFE tube and the fixed parts on both sides to transmit force, so the tangle monitoring module is not effective when the PTFE tube is not fixed.
You can enable the tangle monitoring function in the settings - printing options on the display screen:
This function is enabled by default. If you want to manually test this function, please note:
The normal filament entanglement phenomenon is actually a slow process of the filament changing from loose to tight. If you manually pull the filament back or directly rotate the spool back, it may cause the filament to quickly tighten and cause the extruder gear and filament to slip. The buffering effect of the tangle monitoring module disappears, which can easily lead to "air printing" and print defects.
If filament tangle detection is triggered during printing, there are two types of situations:
The tangle detection function does not support flexible materials, including TPU, TPE, wet water-soluble filaments, and PVA filaments.
Before printing, place the spool correctly on the printer's external holder, send the filament through the PTFE tube to the extruder, and make sure that both sides of the PTFE tube are fixed (the recommended external tray placement is shown below).
The root cause of triggering the tangle monitoring alarm is that the feeding resistance on one side of the tube is too large, and the extruder consumes the filament inside the monitoring module, resulting in spring compression. After the tangle alarm is triggered, check whether the following conditions occur:
1. The filament on the spool is wound and tangled;
2. The spool is placed directly on the table or in the drying oven;
3. The PTFE tube length used is too long or the tube is badly bent.
Avoid materials that are too hard (i.e., too high modulus) or too brittle (i.e., not enough toughness), including third-party fiber reinforcement materials such as PA-CF/GF, PET-CF/GF, and PLA-CF/GF.
Before printing, place the AMS lite next to the printer in the recommended position, as shown below:
After printing with AMS lite and triggering the tangle detection, please check if the following situations cause the feeding resistance on one side of the tube to be too high:
1. The filament on the spool is wound and tangled;
2. The filament is stuck on the edge of the spool;
3. The AMS lite is placed too far, and the PTFE tube is installed incorrectly, resulting in too much bending and too much feeding resistance;
4. The spool is not properly installed on the AMS lite, for example, the spool is placed in the drying oven and the filament is pulled into the AMS lite;
5. The extrusion wheel of the AMS lite feeder has residual debris and needs to be cleaned.