E3Dv6 Replacement for Hexagon Hotend

Thanks, guys! I'll get started on this before my V6 arrives

 

By the way, I wanted to follow up on this! I did indeed complete the replacement, and the printer is working nicely. I ended up using the mod we'd talked about, and after struggling with assembly/disassembly was able to get it running, although I ended up not replacing the top part (no need, really).

I installed the E3D V6 complete with its stock fan, which I connected to the 2nd extruder and enabled through E0_AUTO_FAN_PIN / EXTRUDER_AUTO_FAN_TEMPERATURE / EXTRUDER_AUTO_FAN_SPEED, thanks to @CdRsKuLL 's advice on a different mod that I ended up not making. I thus have the terrible, tiny, misaligned 12V stock Robo fan and the E3D V6 stock fan both actively cooling the hotend.

Speaking of Marlin changes, I also compiled a version based on @WheresWaldo 's branch but using manual mesh bed levelling instead of UBL. For some reason my sensor doesn't seem very reliable between different locations on the bed, so I'm keeping it as just a Z endstop on a fixed position of the bed until I figure out what's going on.

In other software changes, I completely dropped RoboOS. I installed a fresh copy of OctoPi in a new SD card and configured it to work correctly. Once that was done, I took the latest version of the RoboLCD software and modified it not to look for updates and to work with the latest version of Octoprint (there were some changes in how printer profiles are stored in config files). There are still a few bugs to iron out (such as metadata fetching), some stuff to maybe reimplement (the levelling wizard stuff) and some temporary hackery in place, but it's generally functional.

I am now happily printing a Benchy in a filament that before always resulted in clogs due to heat creep (ColorFabb PLA/PHA), in a firmware without any broken custom Robo GCode "features", in a software stack that isn't hopelessly outdated and phoning home for whatever purposes Robo has.