First time PETG, dudes
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Hi,
I am printing PETG for the first time, at a temperature of 240º .... but when it extrudes, I hear a "backfire" in the extruder, like micro explosions ...
This is because the temperature is too high? I have given that the PETG in 230 and 250, is its extrusion temperature
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Dry your PETG !!! It is hydrophobic
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@tecno said in First time PETG, dudes:
Dry your PETG !!! It is hydrophobic
PETG is afraid of water ???
I think you mean hygroscopic. 
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@deckingman said in First time PETG, dudes:
@tecno said in First time PETG, dudes:
Dry your PETG !!! It is hydrophobic
PETG is afraid of water ???
I think you mean hygroscopic. Hydrophobic can also mean repelling water. PETG is generally reckoned to be a hydrophobic material (compared to some) which means actually that it tends not to absorb water - it's the hydrophilic (or hygroscopic, which PETG is not) ones that you really need to manage.
However, it will eventually still absorb some, and drying filament never hurts...
I find PETG maks the cracking noise if I extrude hot and fast into open air - not printing. Even filament relatively recently taken from a vaccum-sealed pack does it a bit in those circumstances. Does it do it when printing, or only when testing extrusion? I'd contemplate turning down the heat a little (but that's a variable that depends upon the particulars of the material).
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The little micro explosions are most likely as some have said absorbed moisture that is boiling off.... most sites will tell you that PETG absorbs moisture quite well so if it's an older roll then it's likely to have a level of moisture.
As for temperature, you really need to test this for yourself on your printer, grab a temperature tower and print it out with varying temps.
I for example print transparent PETG @214c only going up to 220c max when i want it a little more fluid.
So at 214c i can extrude at 12mm cubed flow rate using a 0.6 nozzle, 0.4 layer, 0.8 width at 38mm/s, rock solid layer adhesion, no strings. If i have small holes <6mm then speed gets dropped to 32mm/s. I do run a high flow dragon hotend and can print faster but these setting provide good output, no blobs and at worst very fine hairs.Cheers
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I find that if the PETG sits in the hot-end too long (i.e. printing slowly) it tends to bubble. I have taken advantage of that for some prints by switching print speed to alternate between 50 mm/sec and 15 mm/sec resulting in a horizontally striped print. The higher speed parts of the print are clear and the low speed parts are "frosted".
I'm not sure what's boiling off, but I see identical behavior in freshly opened spools and spools that have been sitting around for months, so it doesn't seem to be absorbing water from the air.
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@achrn said in First time PETG, dudes:
@deckingman said in First time PETG, dudes:
@tecno said in First time PETG, dudes:
Dry your PETG !!! It is hydrophobic
PETG is afraid of water ???
I think you mean hygroscopic. Hydrophobic can also mean repelling water. PETG is generally reckoned to be a hydrophobic material (compared to some) which means actually that it tends not to absorb water - it's the hydrophilic (or hygroscopic, which PETG is not) ones that you really need to manage.
However, it will eventually still absorb some, and drying filament never hurts...
Those two statements are contradictory. The first one is incorrect. PET-G filament is definitely hygroscopic. Take a look at this article.
https://www.matterhackers.com/news/how-to-succeed-when-printing-with-petg-filament
If you scroll down far enough you will come across this statement (quote):
"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,......."
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@mrehorstdmd said in First time PETG, dudes:
I'm not sure what's boiling off, but I see identical behavior in freshly opened spools and spools that have been sitting around for months, so it doesn't seem to be absorbing water from the air.
I'm not a betting man, but I'll wager that it's definitely boiling off water. One of the worse reels of filament I ever had was reel of E-Sun PET-G which was fresh out of it's vacuum foil packaging. I event wrote a post about it on my blog. I eventually gave it it to someone else who spent many days drying it and eventually managed to get some sort of print but it was never great. We concluded that the reel must have fallen into a river before it was retrieved and vacuum packed.
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@deckingman I get shiny, glass-like, transparent prints out of both fresh and long-ago-opened PETG filament as long as I keep print speed above about 25mm/sec. I live in a humid place (in the summer) and it doesn't seem to affect the prints at all. Maybe the filament is already saturated with water. I buy cheap, no-name stuff via amazon.com, and 5 lb spools from Keene Village Plastics, a quality filament maker. I have noticed no difference in the behavior/performance, but maybe the manufacturing processes are similar enough that the spools all arrive with about the same amount of water absorbed into or adsorbed onto them.
I don't have a filament dryer but I do generally keep filament in sealed boxes with CaCl desiccant. If I'm in the middle of a design and printing test parts I usually just leave the spool on the printer, exposed to the air in the room, often with the window open, sometimes for days at a time. Again, no apparent difference in performance.
I am usually running the filament through a volcano heater block with a 1mm nozzle, so maybe that is a contributing factor.
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Thanks,
In the area where I live, Valencia (Spain), on the coast, there is a lot of humidity, it is easy for us to be over 70% ...
It is difficult to keep the filament rolls with low humidity ...
What effects does this humidity have? (on the impression and on the finished piece).
- Only aesthetics?
-Is it more difficult to print? - the backfires when printed?
- Only aesthetics?
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@peirof said in First time PETG, dudes:
Thanks,
In the area where I live, Valencia (Spain), on the coast, there is a lot of humidity, it is easy for us to be over 70% ...
It is difficult to keep the filament rolls with low humidity ...
What effects does this humidity have? (on the impression and on the finished piece).
- Only aesthetics?
-Is it more difficult to print? - the backfires when printed?
I'll post that link one more time. It has all the information you need and will answer all your questions. https://www.matterhackers.com/news/how-to-succeed-when-printing-with-petg-filament
- Only aesthetics?
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@deckingman great article, thx
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@deckingman said in First time PETG, dudes:
@tecno said in First time PETG, dudes:
Dry your PETG !!! It is hydrophobic
PETG is afraid of water ???
I think you mean hygroscopic. Hmmmm marking words you are
I'm just a bloody foreigner making some mistakes.! -
@deckingman said in First time PETG, dudes:
We concluded that the reel must have fallen into a river before it was retrieved and vacuum packed
Apparently some filaments go through water during the manufacturing process.
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@tecno said in First time PETG, dudes:
@deckingman said in First time PETG, dudes:
Hmmmm marking words you are
I'm just a bloody foreigner making some mistakes.!You seem to be upset. In which case I apologise. I've been trying to learn a foreign language myself for many years. Personally I'm quite appreciative when a native of that language points out mistakes that I have made. Especially when it is done in a polite way and with a
. Fear not, I will not try to help again in the future. -
Me upset NO WAY
I appreciate all help as do all others Ian, so just forget my answer that was written with a glimpse in the eye.
Looking forward to be corrected LOL
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@tecno That's OK then. Electronic communications, whether that be forum posts, emails, social media messages, and with or without emojis, can easily be misinterpreted without the subtly nuances of facial expressions.
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I agree, this old fart (a Finn in Sweden) I am a bloody foreigner everywhere L O L
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What is the humidity that is recommended for the filament? Right now there is 70%. And I don't know what value is adapting, or which one I should look for...
Anyway it seems to me a lot, although the filament does not have that level of humidity, it will have enough...
I would like to know what is the maximum humidity and the recommended for printing. What solutions do you use to control humidity? I've seen several:
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bake at low temperature, about 60
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airtight plastic containers
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I solved prepared for roll (on Amazon there are many) some recommended
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others (moving to the Atacama Desert,....)
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