So I got the hot end taken apart after it had a melt down

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.

The teflon tape around the threads is to seal the thing It’s very common…you’ve never threaded a pipe before?

Ya I have, just wanted to make sure.

Why were you taking it apart?

… The heater block blew itself out of the peek housing,…

Anyway all in all we figured it just needs a new 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.

Ya I’m replacing the thermistor with a new one, the one I had in there was fairly new, I have a fan cooling the peek housing.

I auto tuned it twice before I started printing again, printed two items and they came out just fine.

Don’t get me wrong I’m not calling fault on anyone, it just surprised me when it happened. I have a friend that can fab me a new peek housing.

Any suggestions in other good hot ends (jheads still not ruled out as it did last a while and printed really well.)

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 Maybe you should get in contact with him and see if it was from that batch or not.

Ill have to do that when I get a chance, I got mine from but he has been out of stock since after I ordered mine., he is the one that designed the hotend.

As with any J-head, I always suggest ordering from - 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. :slight_smile: