Built another print head.
Reduced the cold/hot transition to as small as practical with this design. It's about 3mm now.
Got really good tolerances on all my parts since I did some work on the drill press. By far, this is the most accurate nozzle I have made.
Press fit the stainless tubing liners. It went in hard. Too hard. Some crumpled under the pressure.
Had just enough stainless to try those again. Got them in, but not to full depth.
Drilled the mounting holes for the nozzle and tapped them out, after assembly this time. That was a mistake for this version as I only have 1mm of clearance between my cold/hot end. I screwed the tap in too far and it impacted the cold-end, which un-seated some of my liners. Bah.
As I had just consumed the remainder of my stainless tubing, I put it in a vise and pressed it back together hoping for the best.
I started it up and loaded 5 colors. Primed it. My nozzle was almost completely blocked with machining garbage (I found out later), so the extrusion literally blew out one of the feed tubes. Cool looking failure though..
After cleaning, it works, but now leaks around 2 of the tubes. Removing/re-seating the tubing is not possible and will destroy it. More tubing is on the way.