@Maxim_Melcher one end of the heatbreak is maintained at near ambient while the other is at 300C. In fact we transition from 300C to 25C in 2mm of distance.
The ptfe is never exposed to high temperatures. All softening and liquifying happens inside metal not ptfe. You don’t need a ptfe lined transition if you have a good heatbreak.
@Sanjay_Mortimer We are grown men. We use PTFE liner. Only I admit it, that my hotends are not “all-metal-1000 ° C-supermega”.
@ThantiK , the video @Maxim_Melcher linked to is why I thought they had a liner inside. Then again, I don’t know much about all metal hotends since I haven’t used one 
Thanks Jeff! Yep, on the current Ubis, the nichrome wire is hand wound in the grooves of a threaded brass rod… Then special epoxy to hold… and the wire has to be threaded through tiny little holes in the custom ceramic insulators… Anyway, it’s time consuming. We’ve made over 30,000 of them… Maybe 40,000. The new one has a neat bobbin to wind the nichrome around and can be semi-automated. It cuts down manufacturing time.
Also, ninja flex didn’t exist when we started 3 years ago… And I wasn’t aware of it when we designed the extruder. We are rolling with the punches. I am really happy to see interest in new materials and glad our new metal Ubis can print them. Btw- polycarbonate is no problem. When you get up and over 300C, you need a thermocouple to stay accurate. Carl is finalizing a special little pcb to handle that if you want to play.
Brook
Matthew, have you filled out a ticket for your hotend issues? I’m interested in getting any failed hotend sin Carl’s hands to investigate. It would be interesting to have a new hotend with only our filament running through it as a control to see if it’s a filament issue.
You mention the age of the hotends, it would be more helpful to hear the total printing hours you have on that hotend.
My gut tells me you are printing a lot of hours, maybe even constantly?? With that many bots, are you running a bot farm to make mass parts? If so, it’s a great place for us to get feedback, even though it’s not a normal use case.
Brook