So I recently installed a genuine E3D V6 (direct) on my AM8 (Anet a8 with upgraded frame). I have already been able to fix most of the print quality problems. But the last one is a hard one for me.
It prints super fine up until a certain height. Then the extruder starts slipping and starts making weird noises like its clogged but I will be able to push through filament properly after cancelling the print. I thought it was heat creep but when touching the spiral heat break it is just a tad warm. I can comfortably put my finger on it and keep it there.
I also tried two different brands of filament and it seems to happen roughly at the same spot.
I tried PID tuning (the temps are literally perfect and super straight with no fluctuations), I tried cleaning the extruder gear and checked if it was worn or anything. Then I tightened everything on the extruder, making sure everything was nice and snug.
I am not exactly a newbie when it comes to fixing my own printer and troubleshooting the problems but this one I have never seen or had before.
Do you guys have any tips for me to point me in the right direction?
Running Marlin 1.1.8. I have a BLTouch on it and an AnyCubic UltraBase.
I have had some similar problems as you describe with my custom build CoreXY printer. I used an all-metal heat break for my 2.85 mm filament width. The heat break clogged up. I found that the inner diameter of the heatbreak, although specifically designed for 3 mm filament narrowed down having a ledge inside. I replaced the heat break with a spare with a teflon tube inside, and never had any problems again.
Since then I scoured the internet to find some proper all metal heat breaks and order a few that do not seem to have that deficiency. I have not tried these (while hot, but when cold the filament also moves better through it and does not get stuck on a ledge or so like the first one), but will when I print POM and ColorFabb PA-CF Low Warp with my soon to arrive Olsson ruby nozzle.