Tip : extrusion stop but nozzle is not clogged ? this can help

Sometime my printer was stopping extruding filament and was finishing the print without error (but it was printing half of the object in the air, extruding nothing).

Each time it happened to me I was thinking that it was related to a nozzle clog, but suprisingly the nozlle was not looking clogged.

I finally found where this problem came from, and that’s the reason of this post, maybe it will help some.

The problem come from the tiny gap between the extruder and the hotend, this gap is made to let the cutter cut the filament.

The problem is that even if both holes are perfecly aligned, Because there is few milimeters gap and also because filament is cutted flat, the filament can get stuck by the border of the input hotend hole, and once stopped it is eaten by the extruder gears wich continu to turn normally.

I have resolved this problem by drilling a bit more the hotend input hole with a little conic drill bit.

Here is the result :

Now even if the filament is bended and cutted flat or holes are not perfectly aligned everything works perfectly, and for now I never had this problem again.

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Good idea to chamfer the entrance to the hotend. This exact situation happened to me the other day. The cutter pushed the filament over which mushroomed the top and it wouldn’t go in when the new filament pushed against it. I had to disassemble the extruder motor to get the piece out that had been chewed up.

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Thank you for this! This ended up being my problem. The print would fail halfway through, but would keep “ghost printing” in the air. After disassembling the hotend and extruder multiple times, I found the issue at the cutting site (on both sides) drilled a conical end like you said, and drilled out the retained filament in the extruder. Works great now!

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