So I got the hot end taken apart after it had a melt down and my friend and I noticed something a little strange about the hot end.
First the threads on the brass tube from the heater block were wrapped in Teflon or fiberglass tape, is this normal or a sign of bad machining? The wite on the threads in the second pic is the tape.
There was also abs on the threads but that was from the heater block shearing out the threads from the peek housing.
The ptfe liner is red which I have not seen yet. How common is a red ptfe liner?
When I got the hot end I noticed the heater block had a slight angle to it while screwed In to the peek housing.
you should check the thermistor too, Usually the heater block pops out when the peek isolator is overheated. The threads become soft and the heater block goes away.
2 things to take into consideration:
1- check your thermistor, see if its reading acuratelly
2- use a fan to cool the peek isolator.
read the temp with a thermocuple or something like that and compare it with what your fw says. You should read it inside the nozzle, as deep as you can. This has happened to me in the past and i found that i was 20c higher than what the fw said.
Also, there was a batch of bad peek isolators (made by brian from http://hotends.com). Maybe you should get in contact with him and see if it was from that batch or not.
As with any J-head, I always suggest ordering from http://hotends.com - he puts up a small batch on Fridays for people to buy from him directly. Though, that does look like his work; the red PTFE I think is unique to him. He’ll even do small modifications if you ask nicely. I had him put a large thermistor hole in mine so I could use the older EPCOS thermistors. A friend had him put a diagonal hole so he could use an axial thermistor. Always good to support someone who’s actually there for the community.