During long prints, my heat block becomes covered in whatever material I am printing. The plastic leaks from the junction between the heat break and the heat block, and runs down towards the nozzle.

I frequently have problems with grinding of filament by the Bowden extruder. However, on the E3D Kraken with a Volcano block, if I use water cooling and a fan positioned just above the heat block, there is no grinding, and everything comes out fine. But the heat block grows a beard of plastic regardless if there is a fan over the heat break or not.

I check my prints once every 2 hours and can wipe the heat block beard, but for overnight prints this isn't possible, so sometimes my prints will have random blobs from when the plastic leaks onto the print.

I have tried multiple nozzles and filaments! I print at only 60 mm/s. Does the volcano block need faster print speeds to prevent this from happening?

I cant really figure out the root of the issue. If the rest of the print comes out fine, then why is there an issue?

  • $\begingroup$ Can you show some pictures? $\endgroup$ Commented Nov 8, 2019 at 5:04
  • 2
    $\begingroup$ Leakage can be caused by untight connection. How do you tighten the heat break in the heater block? This is best done at high temperature, not room temperature. $\endgroup$
    – 0scar
    Commented Nov 8, 2019 at 7:48
  • $\begingroup$ What kind of hotend design are we talking about? $\endgroup$
    – Trish
    Commented Nov 8, 2019 at 16:14
  • $\begingroup$ @Trish it is just a work in progress as I iron out the kinks.. An E3D kraken, water cooled, with a fan, all Bowden extruders -- only using/testing with one of the four available bowdens on the krakens right now. I'm considering that for a while, rather than doing cold pulls, i'll just use a different kraken slot for each material when i need to change materials $\endgroup$
    – K Mmmm
    Commented Nov 8, 2019 at 18:07

1 Answer 1


A video I recently viewed (YouTube link) regarding installing a hot end assembly references the proper sequence of parts placement. Starting with the nozzle, thread it into the heater block until it is proud of the surface by a half of a millimeter, perhaps slightly more. The heat break is then threaded into the heater block until it contacts the nozzle. If not already in place, attach the heat sink.

The next step is to bring the assembly up to maximum temperature and re-tighten the nozzle assembly, obviously using great care due to the high temp.

The video specified that performing this sequence incorrectly would result in leakage from the assembly, which describes your troubles.


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