@Taylor_Landry1 if he said PEKK I would have remembered it. There are a few other high temp plastics in that range, the name escapes me.
Perhaps it’s PAI, trade name Torlon?
@Alex_Skoruppa Have you had enough time with the hotend to give a mini review? Tried printing any high-temp materials with it?
As the principal designer of this hot-end, I can answer a few questions about it:
The brown material is Vespel Polyimide. It is rated as being good to 285 degrees but it appears to be fine at 300 degrees. This material is such a good insulator that the temperature drops about 100 degrees from the heater block to the outer cage. The rest of the heat is quickly eliminated by the external heat sink on the cage. The inner heat break has a wall about 0.011" or less thick. It is very thin, fragile, and the reason why the external cage is needed so as to support it. Once supported it is quite rugged.
The hot-end is, admittedly, expensive to make as the necessary precision is quite high and the Vespel Polyimide is very expensive. That tiny piece of Vespel Polyimide is actually 1/2 the cost of the raw materials of the entire hot-end.
The heat break is so effective that the inner heat sink is about twice as long as necessary. The fins on the inner heat break are very thin (0.020") so as to provide more surface area than normal and they are very efficient. Interestingly enough, the heat drops off a lot faster in the core of this hot-end than on the outside of this hot-end. This was discovered quickly when developing this hot-end and the external heat sink fins were added shortly after this discovery. Once the external heat sink fins were added, heat was no longer an issue.
When I print, I exclusively use this hot-end design as it is very reliable and feature-rich.
While I have made and can make these hot-ends, they are no longer in production and I no longer have anything to do with hotends.com.