Extruder Experimentation

My working theory is that there is a pause in extrusion which leads to a cool down and hence a jam when the motor can't start up again.

Another theory is there is a deflection in the filament within the Bowden cable - and hence stored extrusion pressure - that causes an excessive force to be needed .

Bowden Joint

First, lets see what we can do about the joint between the Bowden tube and the extruder housing. The very nice people at Norgren have the specification for the NSF-51 connector, and within it are assembly instructions. I hope they don't mind if I post them here.

Norgren PNEUFIT® D Assembly Instructions

Using those instructions (i.e. cutting off the 10mm of chewed up Bowden cable, and sinking it past the O-ring) the gap is reduced to about 0.8mm.

End of Bowden Tube.

After Reassembly

While Extruding

That's still not good, because of the play in the tube; ±0.8mm is 5.4mm³ of plastic, but I feel better about it.

However, it doesn't solve the problem and the extrusion still stops mid-print. I also noticed that the gap returns to more than a millimeter while extruding.