Have some strange print quality issues with PETG HF. Dried in AMS HT for 12 hrs. The layer artifacts I’m having trouble tuning out. H2D (1100hrs).4 Nozzle.2 layer height Stock PETG HF profile Any suggestions?
Putting dry vs not dry filament aside - since you already addressed that - what I’m seeing here points to multiple calibration-related failure modes rather than a single defect.
Based on the surface features in the photo, the likely categories are:
- Flow rate mismatch
- Pressure Advance error
- Filament path friction (PTFE / AMS related)
Here’s what I would suggest as troubleshooting steps. Do these in order.
-
Switch to a known-good PETG profile using a different spool. Generic PETG is a good baseline.
- Do not rely on auto calibration.
- If the symptoms change, perform manual filament calibration. Start with flow rate, then Pressure Advance, then temp calibration. Last do a volumetric flow calibration.
-
Remove the AMS from the troubleshooting path.
- Print directly from the external spool holder.
- If the symptoms change with the AMS removed, inspect the entire PTFE path before putting it back into service.
- Look for inner wall wear.
- Verify bend radius, especially near the toolhead. Excess slack right before the toolhead can create a sharper bend, add friction, and show up as flow instability.
-
Inspect the Z screws.
- Clean and lubricate.
- This is less likely the primary cause of the defects shown, but it is easy to rule out and can contribute to inconsistent layer behavior.
Net: all of these artifacts are most commonly explained by improper filament calibration, with mechanical friction as the next most likely contributor. I would rule out calibration first before chasing hardware faults.
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Thank you so much for this detailed reply. I also believe it is a filament calibration issue since I’m not seeing these types of issues with PLA, at least not as noticeable. I will use your suggestions and report back. Appreciate your help
Try increasing nozzle temp to 247, set chamber temp to 43, and nerf your acceleration levels, and make sure zhop disabled.
Why 247 vs 246.375? Or why 43 vs 43.00003? Just asking. 
Hours and hours of testing here… 245 produced horrible prints (under extrusion with a tungsten high-flow nozzle), 252 had problems the other way. 247-250 is the sweet spot, but 247 is safer. If you don’t set the chamber temp with PETG HF, your 12-hour prints will either curl at bed temp <= 72, or you will fry multiple colors in the first layer at >= 74 bed temp. Chamber won’t heat under 40C… But 50C makes stringing worse… Go test yourself…
247C? Or 247F? And settings you work out using high flow tungsten nozzles might not be appropriate for others with stock printers.
You may have good advice to offer but the details like units and other configuration issues are extremely important when giving others advice. Popping in to say set X to 247 without the extra information can be confusing and even incorrect if the user doesn’t have the same configuration.
Maybe, but none of the other threads here were useful when I did my testing…and the stock Bambu profile didn’t work either, so when see someone asking for help, I gave what advice I have…
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When specifying numbers units are important. It used to be that giving an answer without units was marked incorrect even if the number itself was correct. Being ambiguous about C vs F can cause people trouble. And specifying parameters based on nonstandard setups can also mislead people. Always best to include the specifics of what is non-standard up front so other can know if the advice even applies to them or not.
Your moniker suggests an engineering influence and in engineering, specifying units and conditions is kind of foundational. Those guys are meticulous. It just helps keep everyone on the same page.
My experiments with PETG HF. In the first photo the walls/sides have uneven and kind of doughy texture, I had lifting on an edge and there is minor stringing.
The second photo is the same part, same print profile, same filament even - after drying. Walls are flat and smooth, no lifting, hardly any stringing.
The only difference was water in the filament and it wasn’t even all that wet. PETG HF hates water.
Here’s another example of a repair part I printed for a friend. The print started with dry PETG HF and looks ok. I was running low on filament so started another spool drying but it didn’t have time to get as dry as I usually go. You can see the point where the filament ran out and the new spool took over near the middle left hole. (Tiny bit of filament sticking out) The upper part of the print had higher water content during printing. There’s a clear difference between the two spools in how they print. I didn’t check lot numbers but both spools were bought at the same time so maybe even same filament lot.
That’s my experience with PETG HF. Dry it and it prints great with smooth walls. Not dry enough and you get doughy walls or worse.
Maybe the same issue.