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I just bought new eSUN PETg filament. When I started to extrude it, I heard popping sound same as moisture boiling out of it. I don't expect new eSUN vaccum sealed filament having moisture content. Is there any problem with my e3d v6? Is it possible that due to old filament, moisture is residing inside my extruder assembly and new filament is carrying it while extruding? My settings :

  • print temperature: 250 °C,
  • bed temperature: 80 °C,
  • retraction length: 6.5 mm,
  • retraction speed: 25 mm/s,
  • print speed: 10 mm/s,
  • layer height: 25 micron

What do I do in this case? Should I clean the extruder assembly?

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  • $\begingroup$ 10 mm/s print speed is very low, try with at least 50 mm/s. $\endgroup$ – FarO Jan 24 at 13:48
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    $\begingroup$ Do you actually mean 25 micron (0.025 mm)? That's an extremely thin layer height and I doubt PETG's properties admit printing that fine even if your printer could manage. In my experience PETG likes thick layers. $\endgroup$ – R.. GitHub STOP HELPING ICE Jan 24 at 14:28
  • $\begingroup$ Was the spool vacuum sealed before you opened it? Did you put it right from the box onto the printer or did it rest some time? How long did the sealed bag sit on the shelf? $\endgroup$ – Trish Jan 24 at 15:03
  • $\begingroup$ How do you know it's new? might have sat in a warehouse for 5 years $\endgroup$ – Carl Witthoft Jan 24 at 15:30
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It really isn't reasonable to expect moisture to be inside of the extruder assembly; it would be the filament. Assuming there was moisture somewhere, the filament would not have time to absorb it in the short time it is inside of the extruder. Once it got to the hot block, any moisture would steam away and shouldn't give you that snapping sound; the moisture needs to be inside of the filament for that.

Because the filament is inside of a vacuum packed bag with a desiccant doesn't really mean anything if you think about it. The desiccants are typically inside of the spool hole and the plastic bag seals that chamber where the desiccant resides. The filament is on the other side of the spool and the desiccant can't really do anything beyond dry out that pocket of air that it is inside; the filament itself isn't really exposed to the desiccant.

If you can also imagine a balloon, do you know how the air/helium slowly leaks out of it after a few days until you're left with a sad pocket of air loosely contained in a bag of wrinkly rubber? You can imagine your bag that the filament came in as a balloon too, but instead of leaking air out, it is leaching moisture in. This of course takes a really long time and depends on the quality of plastic the bag is made of, its thickness, and the quality and properties of the material the filament is composed of. Because the desiccant isn't between the bag and the filament, as soon as moisture gets in the bag, it's likely it'll be immediately exposed to the filament.

When I first started 3D printing, I opened up a fresh spool of black ABS from ColorCubed. It was nicely vacuum packed and with a silica-gel packet, but after immediately opening it and putting it in my new printer and then printing with it, you could tell it was so saturated with moisture that you'd swear you could wring it out.

It is possible you got a shoddy spool, it is possible that you got a really old spool. I'd advise looking into some techniques to dry out the filament and going from there.

Welcome to the community, by the way!

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250 °C is a bit hot for PETG - It's in the range, but on the hot side. Popping is usually due to moisture. I've had many new, vacuum sealed spools of filament have moisture in them. Try drying it.

I'd recommend a dehydrator rather than an oven; with PETG I wouldn't go over 150 °F.

The problem with an oven is the extreme radiant heat from the elements can (not always) melt or deform the spool or even fuse parts of the filament in the spool together.

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The extruder can't hold much water and transport it to the melt zone. Filament can. The printer behaves like the filament is wet, so try drying it.

Try putting the filament in your electric oven at the lowest temperature (often 170 °F to 180 °F) for an hour and see if the behavior improves.

Keep the filament at a distance from (or shield it from) the heating elements.

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  • $\begingroup$ Remember to keep a really close eye on it too if you're trying to dry it in an oven; I've seen other people who put their spools in the oven to try drying the filament and have the spool itself actually melt and ruin all of the filament, even at low temperatures. $\endgroup$ – TheArchetype Jan 31 at 2:07

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