Implemented Filament Runout Sensor for Direct Drive for 1,75 and 2,85 mm

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The automatic check of the filament fill level is absolutely necessary, since the 3D printer without this feedback would continue with the manufacturing process and thereby losing the print.

The implementation was carried out by means of a pushbutton switch (Fig.: (A, 4)), which was activated by the inserted filament. The state of the switch is changed when there is no fila- ment more in the chamber. Since it was to be assumed that the available lengths of the filaments will be short, the sensor had to be installed very close to the hotend, which is why an integration takes place. The friction of the filament on the tactile switch would cause inconsistencies in the print quality and possible deposits, which is why a button with a guide wheel (Fig.: (A, 3)) was selected. The outer cover of a bicycle valve (Fig.: (A, 2)) was used, with a cutout for the guide roller. This component must be metallic, because the filament experiences a lot of friction in this area. The functionality of the mechanism has been shown in Fig. (B) for 1,75 mm and shown in Fig. (C) for 2,85 mm.