PETG problems on A1 combo

I was getting this terrible problem with the generic PETG profile, and 0.16 optimal settings. This is freshly dried overture PETG filament.

Per somebody’s suggestion, I increased the temperature to 265C and decreased max volumetric rate to 10mm³/s. The issue still happens, but it’s less frequent as you can see here:

I have some Bambu brand PETG on order, and hoping that just works out of the box, but in the meantime any tips to fix this? This is a model I’ve printed countless times with a variety of PETG filaments on a Prusa and a Creality with no problems.

Could it be something in the hotend nozzle is clogged and the increased heat helped somewhat but still slightly clogged? Do you have a spare nozzle of same size to try swapping and retest?

It seems unlikely since it’s a nearly-brand-new machine, and this PETG was the first higher temp filament that was used in it.

I have the hotend set on order and should hopefully get it in a few days so I’ll try it just to be sure.

For the record, if anyone finds this and is having a similar problem: Turning off “slow down for overhangs” in the “SPEED” section fixed this.

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Reduce the max volumetric to 6 and try! But with 250 range temp these printers are too fast for the hotends! Normally ender 3 max vol is 2.5 6 is a good amount of volumetric volume !
It could be better but quick swap nozzles sound with some compromises

Why? I’m getting great prints by turning off the “slow down for overhangs.” Is there additional advantage to less volume?

Print at 270c please for PETG especially on A1 series printer.

Make sure the PETG is super dried before printing. Those said PETG don’t need to dry is a joke. Only PLA doesn’t required.

It was dry, as I noted.
Also, why? Again… I’m getting good results now with the default Bambu PETG profile and turning off the “slow down…” setting.

I think they overread your post saying you sorted it out and wanted to help.

As OP, I think you have the option to mark your post as “Solution”. That usually catches the eye.

I don’t see any way to do that, and am guessing it’s related to the levels/badges/points/whatever this site uses.

Not even when you click the three dots between the “Answer” and the “Edit” button on your post?

Sorry, I have not yet created a thread myself so I am not certain how it is done. It might be related to badges. It would just be sensible that if you have sufficient system trust to open a thread, then you should have sufficient system trust to mark a post as solution or a thread as solved.

I may be blind and missing it, but after I click the “…” this is what I see. It adds a bookmark and private flag.

Many thanks. That looks the same for me. Nothing to flag a solution.

The only other (sensible) place I can imagine is the thread summary below your initial post. But then again, when looking around the forum, I realized that a solution marker one of my posts received was also overlooked. Helpful souls provided further input after a solution was flagged.

If (and only if) it really bothers you, the only other thing I can think of is to repeat your nicely succinct (and hopefully also helpful to other printers) solution at the bottom and make the “fixed this” as eyecatching as you can.

Have you tried printing using the Bambu PETG profile instead of Generic?
I tried a print with some Polymaker PETG yesterday using the Polymaker PETG profile (Identical to the Generic) and midway through, the part lost adhesion and I got a bed full of spaghetti.
Today, I ran the exact same print and filament using the Bambu PETG profile, and it printed perfectly.
There’s two significant differences between the Bambu and Generic profiles:
1: Bed temp is 70 for Bambu, 80 for Generic. Eh, not huge, and oddly in a different direction than I would have tried, but, sure.
2: Cooling fan settings are, IMO, whack for the Generic. General opinion I’ve seen is that PETG should not be aggressively cooled. Bambu settings for part cooling fan: 10 min, 40 max. Generic/Polymaker settings for part cooling fan: 40 min 90 max. WTF?
I have seen many cases of folks finding that the Bambu settings work better than the Generic settings for third-party filaments.

Not sure if this is solved, but for me cleaning the nozzle and using the generic PETG with lower volumetric flow seemed to help a lot…Also, the “dry your filament” obligatory comment.

I really struggled yesterday with printing PETG with a 0.2 nozzle on my A1 mini.

To get it to work nicely I had to:

  • Switch from smooth to textured plate
  • Up bed temp from 70 to 80 (measuring the bed temp with an IR gun showed the bed temp to consistently be 10deg below the target temp)
  • Up nozzle temp from 255 to 265
  • Slow speeds down by 2/3rds and halve volumetric flow
  • Slow accelerations down to 1/10th

All worked very well in the end. I did the changes in three steps (plate/temps/speeds) and all got incrementally better. Ended up in a very nice part.

First failure was bed adhesion, second was lots of stringing and poor layer adhesion, third was vertical spikes where each deposit started that then picked up on the next pass.

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Good to know! Thanks for sharing.

Just got my A1 back up and running after the Heat Bed retrofit… Prior to the retrofit PETG worked really well. Now it’s like the example picture above. I know PETG can be picky with environmental changes (humidity, etc) but was wondering what 2/3 speed would actually be based on your post or what you would recommend the actual speed to be.

If you haven’t already, try the solution that worked for me: turn off slow down for overhangs