I melted my PTFE liner

[darus67]

I got my hot end assembled and decided to test it. I hooked up the Velleman, stuck a thermocouple into the hole opposite the one I
assembled the thermistor into, and cranked it up.
One quarter turn gave me about 100 deg C, according to my thermocouple meter, Half turn gave me about 150 C, 2/3 turn gave me about 200 C, 3/4 turn got me about 250 C. At this point I probably should have left well enough alone seeing as how that is as hot as I'll probably ever need it to get.
But no, I had to crank it up to 300 C. When it hit 300, I turned it back down.

When I was done playing and everything was cool enough to handle, I disassembled the hot end this is what I found:

Melted PTFE

I was surprised because I didn't think 300 C was hot enough to melt PTFE. Am I mistaken on that point, or is my thermocouple meter wrong, and I actually had things significantly hotter than I thought I did?
Or, would everything have been fine if I'd had filament in there?

Here is a photo gallery with a few more shot of my hot end assembly adventures.
https://www.dropbox.com/sh/4i2q07ai9e1j6gk/2IuCWBVDfe

[tom10122]

It melts at 327 c so it's not too far off, I suppose if it was at 300 long then it could melt

[michaellatif]

300 degree C at the thermistor holes means that the inner parts are at a higher temperature. Not surprising that the PTFE started to melt. Good thing the liners come out and are replaceable .

[darus67]

Yes.
That's why I made sure to order spares with my H1.1 kit.