I have been experimenting with NOPHEAD's nozzle design for a couple of weeks. The second picture shows one made with brass and a Peek tube. I had problems with the thermistor coming out so I held it in with twisted wire and fire cement. This worked OK but I melted the Peek when the thermistor fell out also when the nozzle hit the work piece, it bent.
I then put in place mark 2 using a stainless steel tube. This works very well using virtually the same design as nophead but without the cooling fin. It does have a narrowed wall just above the heater block anmd it is tapered at the end. The cooling comes from the plate that the nozzle is mounted into. The tube is made from 8mm stainless studding and the brass is 3/4" bar. It uses the ceramic resistor as a heater and this is sealed at either end with fire cement.
The welding tip is drilled out but is not drilled in as far as it would go as I suggested earlier on and it seems to work.
The great thing about it all is that from deciding to make it to having it heating on my machine using a pillar drill, lathe and taps it only took 90 minutes. Much faster than the old nozzle. Well done Nophead, genius design.