Please help  

PETG sucks up moisture

PETG is very hygroscopic, which means it can easily absorb moisture from the air. This causes a number of print problems, including increased stringing. Before making a bunch of slicer and hardware changes to a setup that was working before, I'd try either another spool (even PLA) or drying your PETG spool. If another spool prints cleanly or drying helps, you know moisture is the cause.

If you still have problems after drying or replacing the spool, there are a number of things you can try to reduce stringing, but it really should only be minor cosmetic stringing at that point.

Post some pics so we can see how bad your problem is.

Update

I have let the print continue… stringing more… seems like the part isn’t affected too much….. what is best way to dry the spool?

Food dehydrator

The most cost effective means is to use a food dehydrator.  

Doesn't look bad at all for PETG

Too bad about your blob of doom - it must have been a doozy.  I've never had one that required replacing the hot end - share pictures it will be fun to see a really bad one.  I've had them the size of a baseball engulfing the heater block, fan shroud and lower fins on the hot end assembly - and they came off pretty easily (only have to be careful near the thermistor wires) 

Surf here for some examples: https://www.flickr.com/groups/14741465@N23/pool/

Update. Filament? Speed increase?

Had a couple failures because the filament tangled in the spool.  Not sure why it wasn’t wrapped better since I got Prusament.  

Now it is looking pretty good… lowered the temp a little bit and stringing got better but still there.  

Couple questions that I am sure have been discussed 100s of times…

1) 6 hours left of a 15 hour print… How safe is it to increase speed?  To what percentage ?

2) probably will need new filament soon… prusament is pricy and I’m annoyed at the tangles in the wrapping.  What is a good brand to get?  Preferably available to buy via Amazon prime … hopefully the orange in the new brand matches up well…

May need a new spool soon

My next spool of orange PETG will be ...

I have a strong tie to the UV characteristics of Prusa Orange, if you don't need Day Glow, there are many options on amazon.  A new one I will be trying next is Jayo/Sunlu orange.  Also, Geetech has a Prusament orange clone in PLA, and have promised one in PETG soon.

California Filaments

I can also recommend California Filaments if you are in the US.  

Tangles

I almost always buy Prusa filaments, they're good quality and they don't gouge you on the shipping (don't know about shipping to US). Very worrying to hear about your tangles, haven't had one myself but I don't print that much. Was it Prusament (manufactured by Prusa) or just Prusa badged third party?

Tangles 99% end user caused

If you think about winding a spool, from start to finish, it's almost impossible to wind in a tangle (a filament loop that results in a knot).  IMO, tangles are caused by losing control of the loose end - it snaps back onto the roll and you pick it up after it has already crossed underneath of another loop. Not saying you didn't experience a tangle.  Just dubious about how it got tangled. 😉

tangles

Prusa makes their own filament.  I agree with Dan, I have never seen a tangle of Prusament that was not caused by me.  I suspect they are very rare on Prusament.

Posted by: @towlerg

I almost always buy Prusa filaments, they're good quality and they don't gouge you on the shipping (don't know about shipping to US). Very worrying to hear about your tangles, haven't had one myself but I don't print that much. Was it Prusament (manufactured by Prusa) or just Prusa badged third party?

Prusamemt

It was prusa made orange petg prusament…

it was weird because it was a brand new roll and printed for 4 hours before there was a problem… I had to untangle it with some difficulty and it looked like it was looped behind other strands like 3-4 times… after that it has gone on for many hours without an issue…

Actual twists from the factory are very (very very) unlikely

Posted by: @ferazr

it was weird because it was a brand new roll and printed for 4 hours before there was a problem… I had to untangle it with some difficulty and it looked like it was looped behind other strands like 3-4 times… after that it has gone on for many hours without an issue…

Please understand that the odds of a mid-spool tangle are extremely unlikely if not impossible to occur given the manufacturing process. It is possible for the end of a spool to become tangled if mishandled. Some crappy brands are very loosely spooled and this can create binding, but this will be apparent the moment you view the spool. However, this is a very rare experience with quality filament brands like Prusament. It might happen to you once, but if it happens regularly, your spool handling procedure is suspect.

Be aware that letting go of the end of the filament for only a moment can cause it to spring back and, if not tightened back up very carefully, create twists and binds. This is really the only way an actual twist -- where the end tucks under a preview coil --can occur. Also be sure not to let the spool spin too freely during printing. If coils come loose and are re-tightened, this can also create mid-spool binding.

This can be a bit overwhelming starting out. I can say that all of my presumed "crappy filament spooling" problems cleared up once I learned to keep control of the end of the filament and ensure it is properly clipped before storing.

Posted by: @dan-rogers

If you think about winding a spool, from start to finish, it's almost impossible to wind in a tangle (a filament loop that results in a knot).  IMO, tangles are caused by losing control of the loose end - it snaps back onto the roll and you pick it up after it has already crossed underneath of another loop. Not saying you didn't experience a tangle.  Just dubious about how it got tangled. 😉

Yes, it's very easy to blame a tangle on the supplier, but if you think of how the spools are wound and packaged, they are wound continuously from a larger supply of filament and as long as someone did not go out of their way to induce a tangle, the new spool of filament will be tangle-free when you get it.

It will be one continuous feed from the center of the destination spool until the machine has measured the quantity to be on the spool.

RE:

Posted by: @bobstro

PETG is very hygroscopic, which means it can easily absorb moisture from the air. This causes a number of print problems, including increased stringing. Before making a bunch of slicer and hardware changes to a setup that was working before, I'd try either another spool (even PLA) or drying your PETG spool. If another spool prints cleanly or drying helps, you know moisture is the cause.

If you still have problems after drying or replacing the spool, there are a number of things you can try to reduce stringing, but it really should only be minor cosmetic stringing at that point.

Post some pics so we can see how bad your problem is.

I am basically a total newbie here and I understand you are highly regarded. That said, I am puzzled. You said PETG is very hygroscopic, meaning it absorbs water, presumably a lot. Elsewhere I have come across info that states, relative to other 3D printing filaments, PETG is not so hygroscopic, much less so than nylon, and even PLA. One web page that listed hygroscopic filaments named 4 and PETG was not among them. So, when you say PETG is vey hygroscopic I am wondering what criteria you're basing this on. I am not arguing but rather as a newbie just trying to make sense of what I am coming across, especially when I run into what appears to be conflicting information.

Thanks

RE: PETG and moisture

Posted by: @russg

[...] You said PETG is very hygroscopic, meaning it absorbs water, presumably a lot. Elsewhere I have come across info that states, relative to other 3D printing filaments, PETG is not so hygroscopic, much less so than nylon, and even PLA. 

It's always good to verify info, particularly some of the "3D printing lore" that goes way back to early experiences. However, my own experiences mirror those that I've found (e.g., Matterhackers) that identify PETG as very hygroscopic:

Many filaments can absorb water from the air and PETG is one of the most notorious. Because PETG is hygroscopic, you need to dry your spool before using it

I experience obvious issues almost immediately if I use wet PETG. A lot is dependent on your local environmental conditions though. My experience in central MA will be very different than somebody using the same material in AZ. 

In short: Be aware of the issues and symptoms and know what to do when and only if it's an issue for you. 

RE:

I've found that PETg, although not as 'thirsty' as PLA, will indeed absorb moisture if exposed to room air.

For me, the tell-tale sign of damp PETg filament is an irregular surface on vertical cylinders.

PETg can be naturally more stringy than other filaments, but if it's significantly stringy, it's probably damp.

Also listen for a popping or clicking sound as the filament is extruded.

A good 12 hour drying in the Ninja Cooker on dehydrate mode at 120F (~50C) will fix it.