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Why PTFE lined throat instead of metal throat?

Posted by Veesta 
Why PTFE lined throat instead of metal throat?
August 07, 2016 07:06AM
Hi there,

Yup, dumb question but i'm interested.

My PTFE throat just arrived and i have two metal throats in the box.

What is the benefit for using PTFE instead of metal?

Also, which end is the nozzle? The open PTFE end or the closed metal end?


I'd guess the open PTFE end should be facing the nozzle?

My extruder is the MK8 thingy, which currently has a metal throat from E3D V6 with a heatbreak.


Edited 1 time(s). Last edit at 08/07/2016 07:06AM by Veesta.
Re: Why PTFE lined throat instead of metal throat?
August 07, 2016 08:06AM
Ptfe is super slippery and some what insulates the filament so that it doesn't soften and clog the throat.it can also withstand up to 450 degrees ferinheit.before degrading and out gassing.
Re: Why PTFE lined throat instead of metal throat?
August 07, 2016 08:26AM
About 230°C, that is good to know. smiling smiley

So, PTFE prevents this form happening? And even if it does, it might still push through?

I have some problems printing. A large surface infills nicely, but small details like screw holes and thin walls might stop extruding -> it will grind into the filament.
And once i pull the filament out, the tip looks like that. The tip is melted and thicker.

(On successful prints, tip looks different)
I have played with the temperatures, but it seems like the temperature good for small details is not good for large surfaces. (And vice versa)

I hope this will solve that problem then. smiling smiley

Edited 1 time(s). Last edit at 08/07/2016 08:27AM by Veesta.
Re: Why PTFE lined throat instead of metal throat?
August 07, 2016 11:18AM
It should help a lot, even though ptfe expands a lot, roughly 1 eighth on an inch for every 100degrees ferinheit per foot, it has almost no friction. That's why is was used in cook ware for so long and is still used for high quality linear slides. It is also really soft and will deform to mechanical defects easily . So if the movement is tight just work it for a while and it will be supper smooth. So even if the filament swells in the throat from heat and back pressure it shouldn't stick and still move into the nozzle.

Edited 1 time(s). Last edit at 08/07/2016 11:20AM by lockezio.
Re: Why PTFE lined throat instead of metal throat?
August 09, 2016 09:59AM
Aww, shit...

These PTFE lined tubes are fragile! angry smiley
Broke the throat when tightening it.

-> to eBays! again... This time maybe few more tubes?
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