Hiya all - New to the Forum, and about 6 months in 3D printing, but a Maker from Waaaaay back… 
Sorry slightly long post here…Thanks in advanced.
I just recently installed a Diamond Hotend on an Anet A8 - as a part of a build I am doing of a far larger scale Ultimaker clone. But printing something the other day, it finished the print then retracted the Z axis a few millimeters, then as a I turned away then back I noticed smoke and a whole lot of Melted Liquid filament run down the side of the print…and it appeared to be bubbling. Just wondering if anyone else has run into similar problems either with this style of print head, or others, and might have any suggestions to alleviate it
It was almost as though the 200 Degree print temp I had it set to had all of a sudden increased to far more than this and Burnt the PLA…
I noticed when pressing on what looked like melted candle wax down the side of the print after it cooled that pressing on it it was quite brittle, almost like Sap on a tree, as it appeared to have been Crystalised (presumably a resulting property of the cornstarch when burnt.)
What makes it hard to imagine that the Print head suddenly jumped to this higher temperature is that Octoprint showed the same temp through the print (with slight deviations of course.) - then when the print was over it didn’t spike…But not only that, the Diamond Head takes far longer to “spool up” and if anything due to the good cooling I have in the venturi it actually cools down rather quick (hence why it takes so long to get to temp…)
I had a theory:
Maybe it is something like the location of the Temp sensor potentially getting a direct stream from the cooling fan through a gap, so showing a temp lower than what is at the Nozzle itself…and then when the print was finished and the Extruder retracted - the filament still in the final end of the nozzle heated to Liquid temperature due to also being stationary, but potentially cooling at the tip and within the “lava tubes” I call them in the DH, closer to the Cooled area in the venturis . Therefore building up pressure and eventually bursting out the tip where it was still not as cool as the top of the Head. Because that is what actually alerted me to look back at it, I heard a small fizzle sound, then saw the molten filament. It was just like a how Lava acts…
I wonder if I just need to either Lower my temp - I had noticed that this print was a little wonky, and the sides were not smoothy, but a little bumpy. The 2 changes I made compared to 2 previous prints were a higher temp by 10 degrees, and increased Filament feed rate from 95% to 105% as I saw with the previous print it looked a little under extruded…
I’m far less concerned if the prints don’t work, the biggest concern was just the Smoke and Molten aspect, which could definitely ruin my day in a hurry - Bad enough that I spent 40 minutes last night trying to find which Smoke Alarm in the house was beeping due to a flat battery…Last thing I want is to need to rely on them!!!
