PETG HF clumping

[KevinMacDonald]

All my attempts to print with PETG HF or CR are resulting in numerous clumping errors, resulting in the print pausing. During a 2 hour print I can expect it to happen half a dozen times. It’s happening now with a brand new spool of BambuLab PETG HF fresh out of the vacuum sealed bag.

I’ve tried Standard and Sport. I have no idea what profile settings to modify. There are endless combinations of speed, fan speed, cooling etc etc etc.

My H2D Pro is brand new. I got it within the last month.

Any suggestions?

[lion7718]

@KevinMacDonald

It’s happening now with a brand new spool of BambuLab PETG HF fresh out of the vacuum sealed bag.

So, You didn’t dry it.

PETG HF

[KevinMacDonald]

hmm ok. Even if it arrives in a vacuum sealed bag, and I just took it out of the bag, I should dry it. Fair enough.

[EnoTheThracian]

Its the bags. They do not complety stop moisture. So after a while sitting dockside and spending a lot of time on the 7 seas…

[anon88136036]

There are lots of issues with PETG and bambu, so some questions first

What profile for PETG are you using?
What bed temp
What nozzle temp
Is filament in an AMS, if so what is moisture reading?

PETG does need to be dry, but often it does not need to be dried before use, but its recommended to dry before use,

Not sure on the H2 series, I have a P2 but the printing PETG on the P2 needs a lot of custom profile work, so might be similar for H2 series,

I had nozzle clumping to the point it wrecked my prints, wrecked a nozzle and burned through 2 silicone socks,

The majority of users who responded to my post blamed me for having a dirty bed, which was utter rubbish and a useless response. Most of the time you do not need to dry a spool of filament, I generally don’t. Not for decent brands of filament, but drying it first is a good idea.

[Jenkins]

as one forum member once put it: “they all come with free water”

[anon88136036]

I have found the most common issue with wet filament is extruder clog, not clumping or any other issue.

Wet filament clogged up my extruder, because wet filament conducts heat far better than dry filament, so the heat creeps up the filament and causes the filament in the extruder to deform. This happens either before the printer started printing, or very quickly once it started printing, as the nozzle heats up a couple of times before printing occurs, wet filament then caused the extruder clog the minute it tried to extrude.

I have found the most common reason for PETG clumping is the fact its oozing out the nozzle too much, too easily. Bad profile settings, not wet filament. retraction is turn off by default in BL Studio, you need it turned on, plus other settings,

I have never dried a filament from a decent brand if it comes in a sealed bag with silica gel in the bag and they work fine each time, but you do have to keep the filaments dry once they are open from the factory seal.

[MZip]

I think it was @NeverDie who did the experiment but apologies if misattributing - if you take a ziplock bag, put a hygrometer in it, and fill it with dry air, the humidity plummets (dry air) but then fairly soon will start to rise and in a few hours the humidity inside the bag will be very close to outside humidity.

Thin plastic is fairly permeable to water vapor. Shockingly permeable actually. It was surprising to me they leaked that bad but they do and it’s easy to do the experiment and see for yourself.

Caveats - ever noticed the metallic coating inside a potato chip bag? There’s many coatings used in the food industry to block oxygen, moisture, probably sulfur and other things. Some coating are invisible to the eye but others like the metalizing are obvious.

The poly bags Bambu uses are apparently only semi-tight for water. The desiccant they pack with the spool will scavenge water that does leak in to an extent but the more water leaks in the higher the humidity. Depending on how long since it was packed and the environment it was stored in, spools can be pretty much any level of moisture in the filament.

Every spool I’ve taken out of a bag to dry has had some amount of water in it. Some was still ok to print with but not all by any means.

[anon88136036]

I agree with the fact most plastic allow moisture to slowly get inside, this has never been in dispute, as that’s why they ship silica gel packets inside most sealed plastic bags, to absorb the moisture that gets in to the bag. That’s also why you should put silica gel packets in with your spool in a sealed bag or box. As moisture will get in, no denying that. Silica gel is a cheap option, rechargeable silica even better.

Chances are a new spool from a decent brand is fine to print with, but depending on your environment, how you store it, lots of variables actually you need to adopt a care routine for your filaments, as once out of their factory sealed bag they will absorb moisture, no stopping it.

If you use up the spool quickly, I have done this a few times, 1KG for me is gone in about 30 hours then I never had to dry it at all.

But if your filament sits, some of my colours I hardly use, or translucent for example can sit for months without me using it, so proper storage is the way to do it. I also run my AMS drier every night, because why not? The ones that are not in use anyway. Thats because the room I have my printer and spools in sits at 40-45% humidity, Which I am not going to change,

I have 2 KGs of rechargable silica gel in my car, a convertible which is not stored in a garage, I have to dry the gel out every 2 weeks.

My point was a care routine is vital, adopt what works best for you, but wet filament does not cause clumping, basically. If the filament was that wet, it would clog in your extruder. So dry the filament out, check the settings of the profile.

I have printed several large PETG prints over last few days, once I got my settings nailed in, PETG is perfect and my nozzle is clean, I qwrecked ,y last nozzle with bad settings.

[MZip]

@anon88136036

this has never been in dispute

Wanna bet?

@anon88136036

I have 2 KGs of rechargable silica gel in my car, a convertible which is not stored in a garage, I have to dry the gel out every 2 weeks.

Just guessing but I bet if you tested your car silica gel after 24 hours (put it in a sealed impermeable container with a hygrometer) it would show it had already equilibrated with ambient humidity. You could test with a hygrometer every couple of hours to verify or disprove.

I do believe people see “clumping” with wet PETG HF though. What OP might be describing are the little ball-like clumps that get left on a surface after water in the filament vaporizes and pushes out a little blob of filament it wasn’t supposed to. In extreme cases you can even hear the sizzling/popping. A number of reports of that here.

But absolutely correct that filament can take some care and feeding if ambient humidity is high enough to cause print issues. It can save a bunch of trouble too. A lot of people can tune out moisture effects when they are on the edge but it’s compensating for something that can change so can have people chasing humidity issues with test pieces for various things.

[KevinMacDonald]

I believe yes, I am seeing PETG ooze out of the nozzle too much. The profile I am using is the “Bambu PETG HF @BBL H2D 0.6 nozzle”. I’m typically printing PETG HF (and sometimes CF) using a 0.6 HF nozzle. Should I re-iterate all of those profile settings here? Seems like a lot.

You mentioned “Retraction is turned off by default. Turn it on. Plus other settings…”?

I will scan through that profile looking for the word “retraction” in the setting name and see what I find. As for other settings, I dunno. Perhaps you can share what you think are the critical settings I should be modifying?

Thank you!

[KevinMacDonald]

After an overnight drying of the PETG HF in my AMS 2 Pro so far I am 2 hrs into a 4 hour print, and it looks flawless.

Also, I have rather an excess of AMS slots for what I need. I printed a dessicant container that is the exact size of a standard spool and I’m currently occupying a slot with it alongside the PETG. I’m thinking about just keeping a big bunch of dessicant inside the AMS at all times with the moisture sensitive varieties - plus regular dry cycles.

[lion7718]

@KevinMacDonald

After an overnight drying of the PETG HF in my AMS 2 Pro so far I am 2 hrs into a 4 hour print, and it looks flawless.

[KevinMacDonald]

It was in fact flawless. So, I learned my lesson. PETG wants to be effing DRY!!

[MZip]

PETG is more extreme but depending on your environment, you may see improvements printing with other filaments that are well dried and have to do less fiddling to print with them.

The reason is you can tune out some water issues but those can vary from spool to spool if not drying. Effects/symptoms can come and go. Drying all filaments may give more consistent and better results even if able to print pretty well undried.

[Assy_87]

I printed with PETG for the first time this week. I dried the Bambulab PETG HF directly for 8 hours at 65 degrees Celsius. Then I did a 12-hour print to print the filament dry boxes for the AMS-2. No problems. No stringing, no clogging. All with a 0.4 HF nozzle.

Two days later, I started another print that also took 11 hours. This one also ran without any problems.

It is very important to dry the filament before use. I have an external drying device (Chitu) that works wonderfully for this.

Greetings