BIQU B1 Hotend fix

This is a hotend fix for the BIQU B1.

#How it works:

Filament travels from the extruder, through the bowden tube, down the hotend, through the heatbreak and into the melt-zone where it is pushed out of the nozzle.

In most printers this whole path is lined with PTFE (or bowden) tube as it offers very little resistance to the movement of the filament. If the PTFE tube is not pushed very tightly against the top of the nozzle then it is possible for filament to leak out and make contact with the metal walls of the heatbreak.

This filament then gets stuck there and starts to create a bulge which interferes with the flow of the filament that is being extruded. If this happens then the net result is that you get inconsistent flow and regular jams. To prevent this from happening it is best to not rely on the teeth of the bowden coupler at the top of the hotend to hold the PTFE tube in place against the nozzle. Instead, it is better to force the PTFE tube against the nozzle using t