Simply use kapton on your hot end !
My head came pre-assembled but it had a small leak between the Peek isolation and the aluminium heating block, that appeared at high temperatures. This resulted in oxydized PLA liquid (the brown juice that becomes crusty when cold), and it dropped on my prints, leaving a dirty dark trace in the object.
I first wrapped the peek and heating element with aIn any case I see no reason to do otherwise now. paper towel. But I had to change it often, and it becomes so dry that I was fearing it could start burning with the smallest trigger. But the leak finally reduced on its own.
What I finally used are two strips of Kapton scotch. I place them opposite to each other on the nozzle, very close to the output, and bend them upwards loosely.
50mm x 100ft Kapton Tape ($8.30 en ebay)
In the end I got more benefits :
- it keeps the brown juice from flowing (as it solidifies before reaching the end of the nozzle)
- I burn myself less often !
- it isolates the head a bit against the fan. For this, I usually try to leave some air between the Kapton and the metallic parts of the head (not quite on this picture though)
- and finally and more important to me now, the PLA no more sticks to the hot nozzle as it was before (especially when priming the extrusion). This makes life much easier ;)
Regarding burns and better heat insulation, an improvement would be to add pieces of glass fiber or kapton tape wrapped around a thin metallic wire mesh.
In any case I'll keep using kapton there for now.