Recovering from the blob  

New Member

Our workhorse Mk2 had the misfortune of a huge blob on the back of the hot end.  I got the blob off but ever since the printer is not working right.  It now drops blobs of previously used filament in the print being done, it will drop clear blobs of filament into a layer when it is higher up that will stop the print and knock prints off, nothing seems to be going right.  I have taken it apart and cleaned up inside the mount (there was a fair bit of filament in there) but it continues to do the same thing once put back together.  The temperature is good (no problems there) but the prints are sucking (prints great for the first few layers).

What am I looking for - what do I need to change out.  I am going to go back over this with the hot gun and tweezers today to get out all of the filament.

Posted : 27/02/2020 5:34 pm
Famed Member

If you had to do a teardown to clean it up, it's possible you didn't get the hotend together properly. Your description sounds like typical oozing that can occur if the nozzle is not properly tightened against the heatbreak. Open your extruder up so you can view the entire hotend assembly. Inspect the gap between the heater block (that the nozzle screws into) and the heat sink (with the fins). The heatbreak provides the transition between the cold top part and hot bottom part. If you see filament oozing out between the block and fins, that means your nozzle isn't properly tight and filament is working its way up out of the top of the block, dripping randomly onto your prints below.

Also inspect the nozzle. The hex collar on the nozzle should not be tightened up flush against the heater block. There should be a small gap between the hex and heater block after tightening at 285C. It is important that the nozzle is tightened against the heatbreak at 285C for a good seal. The heater block should function as a nut holding the nozzle and heatbreak together. (The similar sounding names don't help.)

Look up the E3D nozzle change procedure for details.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 27/02/2020 6:16 pm
Member Moderator

moving the thread to english forum, there is a higher chance for more answers.

nevertheless @Bobstro, thanks for valuable answers

even an old man can learn new things 🙂
Standard I3 mk3s, FW 3.8.1, no closed box, sketchup , fusion 360, PrusaSlicer, Windows 10
Posted : 03/03/2020 4:27 pm

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