(Also posted to /r/3dprinting) I had some good results with a spool of clear

3D Printing
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(Also posted to /r/3dprinting)

I had some good results with a spool of clear XT when I first got it by using the same settings I’d used previously with T-Glase: 240 C at 40 mm/s.

I left the spool on the machine for a few weeks and now coming back to it I can’t get it to complete a print no matter what I try. It seems to build up too much back pressure in the hotend until the extruder starts stripping the filament and jams completely. I’ve tried higher temperatures and slower speeds but so far with no luck.

Could it be the filament had absorbed too much moisture? Folks say PET is relatively impervious to moisture, but I can’t think of anything else that might’ve changed.

Any advice/experience you’d care to share?

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Clean your nozzle…

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@denix Thanks, but tried that and switching nozzles.

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PET has a very high moisture absorption which causes its decomposition in the nozzle and that what’s clogging it. I recommend drying the filament, not sure about the temperature since PET can get sticky which can cause filament stick to itself.

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Thanks @jenia_zelikman ​, can you point me to any references for that info? Matthew from @PrintedSolid ​ seems to believe otherwise. I plan to dry this spool out and try again.

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@John_Davis you can find the information in the Wikipedia article on PET

Under “drying”
Since I have a PhD in Materials Science and deal with Polymers as a professional for more than 15 years I can tell that it is accurate.

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@jenia_zelikman Excellent, thanks for the info!