So I finally got fed up with the worn nozzle on my Robo C2, and decided to do something about it. I bought a replacement hotend shortly after buying the C2, but decided not to waste a perfectly good hotend when all it needed was a good replacement nozzle.
At some point, I remembered that I had a spare E3D nozzle waiting to be used, originally purchased with a v6 hotend. Forgot that it was a 0.25 mm nozzle, not 0.3 as I had mis-remembered. But I did a bit of research and found that E3D nozzles will work in the Robo hexagon hotend, as the threading was the same.
Side note: I really need to invest in a set of MicroSwiss nozzles for the C2. Hardened and/or coated steel will help me avoid the kind of wear-and-tear that comes with printing with abrasive filaments like carbon fiber, glow in the dark, and Amolen marble filament.
Swapping out nozzles was pretty easy; it just required a little bit of torque to get the old nozzle unstuck. The E3D nozzle was much easier to install as it was friendlier to my little spanners from more angles.
After changing the onboard printer profile to reflect the new nozzle diameter (via OctoPrint), I created a new printer profile in Simplify3D. Reduced the maximum print speed to 2400 mm/min (40 mm/s) and tweaked a few other things. And, oh yeah, set the Z offset. Layer height is 0.06 mm.
The first thing I printed was a set of saddle plugs for my wife (not in the gallery). Those were ultra smooth with good detail on the designs. Then it was on to a 3D Benchy in eSun cool white PLA+ where you can actually read the sign on the back of the boat.
The final test model I printed was the infamous tree frog in Makerbot translucent red, using Simplify3D’s full honeycomb infill. There were some bridging problems between the frog’s eyes, a problem I’ve encountered before when using this kind of infill. Probably needs more solid top layers or tweaking the bridging parameters, but I wanted to push the machine a little bit anyway.
It really feels like a brand new printer, and I’m looking forward to trying out some new hyper-detailed prints on this thing…
Any suggestions? 
https://photos.app.goo.gl/SStcyemOIxd1BxPi1