Why are my consistent overhang issues getting worse?

I have printed the exhaust fan mod 4 times now. 3 times with the recommended settings of quality layer height .16, strength top/bottom layers 6, with the default for overhang enabled. It got worse and worse with each print in the area I marked. This last print (one shown) is the worst when I tried changing the variable layer height to make the speed consistent across all layers for the entire print. It was strange it started only messing up on one side of that overhang, then it just progressively get’s worse. I’ve done this over 2 days, with the same filament and room temps. Please help?

Here are the other 3 prints, the very top being the first, and the very bottom which looks better; I printed and flipped 180 so the part was upside down. The middle print was with the same exact settings as the first, printed 3 hours after once the printer cooled down.

It’s not supposed to have these problems according to printables also with no support. So I have to wonder if something is up with my printer or settings.

I have not printed these but had a steep learning curve with Bambu’s PETG on overhangs recently.

From the screenshot, you have 2 PLAs and 2 PETGs loaded while the nozzle temp indicates the PETG recommended temp.

If you have the problem with Bambus PETG, try going down to 245°C and lower printing speeds. Nowadays I dial in 25% speed for PETG as raising cooling leads to overhang warping, particularly on sharp overhangs.

If it is PLA print, I’d also recommend lowering speed and nozzle temp but can’t give specific values.

Bambu advertises their printers for their speed which requires higher nozzle temps. Personally however, I have found their precision, reliabilty and durability to be more important though. For a given time, I prefer a single good part to four bad ones :wink:

Thank you this is very helpful! Yes, I am just trying to print with PETG only right now since that’s going to be my most popular material for my use. So I want to learn how to handle all the issues as much as possible. I’ve printed 4; the one last night is even worse! I would have imagined setting variable layer height to adaptive and lowering the radius would have improved the print some. In my pics, the flow rate looks right super low for overhang and high for walls.

I’m doing one more print now on my second Bambu X1C; the same exact printer setup is just one month old vs my current printer is a week old. I will report back to see if keeping the same parameters but using a different X1C makes any difference. If that doesn’t work, I will try what you suggested, which is lowering my print speed. My overhang speed for 75-100% is 10mm/s which is what it should be running at?? Why I’m confused? That’s why we have this forum really enjoy how knowledgeable everyone is.

I assume that you have your lid and door closed?

I always leave my door open, when printing PLA and PETG.

I keep my thumbs pressed and fingers crossed :crossed_fingers:

In my (limited) experience, lowering the temperature is the most important for overhangs. Bambu gives an almost 20% recommended temp range for PETG on their rolls while others tend to have a lower range of around 10% (starting lower too).

The speed for overhangs is a good feature but the speed change is rather sudden, leading to visible line width changes (as the thermal response in the nozzle is nowhere near as quick). For that reason, I just went with a very low outer wall speed of 30 mm/s and disabled overhang speeds.

I probaby could have gone faster, but my current print is a 3 day print which I want to get right.

Due to warping, I only use 10% part cooling, have the chamber fan at 70% (initially at 10% due to warp-promoting lower part geometry) but switched on the Aux fan for reasonably even layer cooling at 80%. The latter had the early layer advantage of actually raising the chamber temp (reduced warping) by pumping heat evenly from just below the bed to the build space.

Still a few hours to go in this long print, but the difference made by a cooler nozzle temp and a low speed are obvious already.


I printed the same exact print on my second Bambu X1C AMS and it printed a bit better than all my previous, but it still has some issues down the side of the front slant or that angle down on the front. I will upload so it shows. It’s good enough for my own needs, but again I don’t understand why 2 brand new Bambu X1C’s can’t print this with the settings recommended on printables with Bambu filament. Guess I will just have to slow the print down and try some other tweaks. Thanks for all the help!

If you look at my other prints attached, one is PLA-CF, and other is PLA (white) they are absolutely perfect. This thing prints CF like nobody’s business.

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Very nice prints indeed :smiley:

I have not yet tried the -CF materials but was really impressed with PLA performance. Even managed to print with Fiberlogy BVOH support interfaces :smiley:

PETG… I still have a bit to learn. Settings are tricky to get good enough.

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Wow, those look incredible!

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