So, I have been playing around with ideas, and this one came up tops (for now)
There are a couple of concerns though, not least of which PTFE creep… apparently Teflon does not have a polymer “memory” and might flow like glass given time and pressure. Will have to do some serious testing – at least there is time for that.
Then there is the issue of the 1mm aperture. The 0.8 refers to the wire that gets fed though it, and not the actual hole size. Found some ancient (2005) reprap hot end literature, and the way they made the hole smaller was quite interesting. They melted some lead-free solder into the hole, while keeping it open with stainless steel wire, chosen for it’s diameter. The solder does not stick to the stainless, and allows the maker to pull the wire out afterwards, leaving a perfect hole.
This is unfortunately not viable with the high speed / high temperature operation people are forcing out of the hot-ends with the latest firmwares, like Sprinter. The solder would just melt out again. Got some ideas from it though… Watch this space.