To start I have an A1. I am using Grey Sunlu PLA Matte. I started using the stock software settings for Bambu PLA Matte. I am printing a 6" by 6" by 1/4" base for a modular terrain system. The final product is still functional but I really want to know what is going wrong. There is a lip around the entirety of the top layer or so of the print which is baffling because when I print a different 1" by 1" by 2" cube there is almost zero lip. Also the edges of the base piece try with all their might despite my many protests to curl up off the build plate.
I have tried the following. Slowly lowering the fan speed, all the way down to ZERO fan (except on bridges), raising the bed temp, raising the bed temp followed by lowering the layer temps, adding the brim (which helped but did not eliminate the corner warping), adjusting the Z offset (within the machine code) a further -0.01, and increasing the top surface speed to match the internal solid infill speed (250mm/s in this case).
These did help a bit with the pulling up of the corners, but seemed even if only ever so slightly to make that lip around the edge of the part worse. I will give some of the basic parameters that I can think might be helpful in solving this issue. At this point I am pretty sure it has to do with temperature, but I am lost on what to do. Any help would be greatly appreciated!
The base layer going on smooth as butter, and according to the charts is in the “perfect zone” for Z offset / extrusion.
Here is all the nitty gritty details of the parameters I used:
Bambu Labs A1 - Purchased this year, rails lubricated last week
Sunlu Grey Matte PLA
Ambient temp in my garage (where the printer is) between 88 and 94 F
Relative humidity is between 50 and 55 % (Measured with a hygrometer)
Bed Temp: 65 C
Filament Temp: 220 C
Final thoughts from me is to put the darn thing in a perfect temperature controlled vacuum and I am not convinced that would work haha! Thank you again in advance to any and all that read this way too long post and choose to provide some feedback. -May your prints never fail!
Thanks for providing so much detailed information with your question. That really helps
What I assume you are seeing is basic warping. When the corners and edges lift up, the higher layers are no longer printed at their specified layer height. With less available height than specified, the printer will have a slight overextrusion at the top edges and in particular the corners. While this usually leads to wavy flow lines on the top, mild warping can lead to the excess material forming an edge.
The next question would then be why it predominantly occurs on large prints. Being caused by the uneven cool down of FDM prints, it is also dependant on the materials coefficient of thermal expansion and therefore a fractional value. And 15% of say a 20cm base is more than 15% of, for example, a 5cm base.
The next thing is, what to do about warping.
To cover the essential basics, the filament needs to be dry. There’s not much point in tweaking things for filament that may be moist.
In quite a few cases, the major problem is build plate adhesion. That does not seem to be the case here, but just to cover the basics it should be mentioned. Mouse ears and brims can help somewhat, but again, the plate needs to be clean.
Next, we need to control the cool down. So we want to print in an environment that is warm while at the same time avoiding heat creep. With ironing or many retracts, <35°C seems to be good while without these 35-39°C is my sweet spot. With the A1 as-is, there’s of course little chance to achieve this without a print enclosure or printer tent. Just remember to use a warm room if you can and keep it away from drafts.
Further cool down control can be done by not controlling the heat that goes put, but the heat input. This gives us the ability to trade print time with warping while maintaining stuff such as layer adhesion, etc. All we need to do is decrease the printing speed and/or layer height except for the first layer. Since both have volumetric effects, they are quite powerful.
Thank you very much for your well thought out, informative, and timely response! Thank you sincerely for the definition update “pulling” is “warping” in this case. If one is to join a community, one should know the lingo.
To start I cleaned the snot out of my build plate. Dawn soap with a good “scuz brushing”, followed by a generous wipe with 99.9% IPA and a paper towel. I am usually very good at keeping the plate clean, but I went a little extra for the test run.
From your suggestions I started a new print this morning with the following changes: I changed the layer height (I left the initial layer height at .2) from .2 to .16 (some additional research said that, that little of a change probably wont do much. However, I felt that with the addition of the other changes along with it, this would be potentially sufficient). I reduced all of the print speeds to 75% of their previous values, with the exception of travel speeds. Finally I turned the fans back up to 60% of their max speed threshold and 2% minimum speed threshold.
This run had the least amount of warping in any of my previous, but it still existed.
I think you may still have that problem with the top surface lip. I think your issue is a 5% infill and only 2 walls. The print shrinks as it cools. You’re printing layers pretty quickly until you get to the top layers. The top layer takes substantially longer time to print, and while the printhead is following the actual dimensions of the print, the layers below are getting smaller. If I’m right, you need to increase infill (or go solid). Doing that will reduce the time delta between the lower layers and the top layer so overall print times (and rate of heat loss) are closer to the same. Also, a higher density infill will stay hotter longer. More walls and higher density infill will also resist the shrinkage effect a little better (but may increase tendency to warp because more plastic = more force when it does shrink. You might need a brim).
I don’t see wall order in any of your screen grabs. If you’re doing infill first, switch it to inner/outer/infill.
I think others are correct w/ the layer time analysis. This is basically a “benchy hull line” but on top.
As for dealing with the lip on your alreadyt-printed pieces, use this “Deburring tool”, one quick zip across the edge will get rid of it (also helpful for brim removal)
When I originally had downloaded the .stl and the person who created the file has the infill set to 5% I was very skeptical. However, after a few prints going well I left it alone. Then I got to the base plate. How much infill would you think to start? I am assuming quite a bit since you suggested solid. Most of my other prints are usually around 25% infill. Do you think this infill increase in tandem with the slower speed settings is optimal? Or just increasing the infill?
Excellent idea! I do have one that I used on metal in a machine shop I worked for a while back, probably need some better blades at this point though. Thank you!
If what you’re already trying doesn’t work, I’d try turning on Infill First and Inner/Outer wall order, and I’d bump the infill up to 33% at first, see if things improve.
Okay, so at 15% infill there wasn’t a huge difference. However, using my fingernail it did feel like the lip was slightly lessened. Unfortunately I have run out of grey, but I do have black…so ill be switching to that, probably wont see the details as well though.
Yes, there’s still a little bit of warping present, but nothing that would explain such a massive lip.
So I concur with @RocketSled diagnosis and defer to his experiences.
Just two questions/comments:
What top layer flow do you have? I could not see that in the screenshots (or missed it). I doubt it is related to that as it would only explain a single top layer expansion.
What is the temp in the room you are printing in? For PLA, I usually target 35-39°C in my X1’s build chamber which helps with a lot of issues. Not really practical for an A1 though unless using a print tent/enclosure.
And a question for @RocketSled as I am trying to better understand this defect and workable remedies: Would it not achieve the same effect as increasing the infill density to slow down print speeds (i.e. increase layer times) below the top surfaces?
The printer is currently in my garage, which fluctuates between 88F (31C) in the morning to just over 100F (38C) in the afternoon. Which it is currently. With the door remaining closed there isn’t any rapid temperature swings, however it is clearly a little hot.
I just ordered an enclosure on amazon and intend on moving it back into the house. Hopefully with the enclosure it will not suffer as bad from warping that it was previously. The entire reason for me moving out into the garage anyway.
The goal is to make the layers below the top surface take more time and retain more heat, so the time is closer to the time required to print the top surface(s) and the thermal contraction is reduced… Speed alone probably won’t do it.
I got my enclosure in today…but of course work went much longer than expected. So Ill set it up tomorrow morning hopefully and get a print rolling to see what the temp difference might do, in addition to any other changes you guys recommend. Thanks everyone for sticking with me. Sincerely appreciate it!
I’m curious if you measure with calipers at the innermost of this inwardly-bent wall, how much it’s actually shrinking vs the 3mf dimensions. It sure feels like a lot.
I do not have any calipers on hand, but with a tape measure and my trusty eye it seems the middle has shrunk about 1/32, 0.032. The top and bottom are spot on the 6" mark. I will drop the infill a bit (save a little time and filament), probably bring the speed back up, and try 4, maybe 6 walls this go around…see where that puts us.
While not perfect (there’s a slight, sharp lip which I explain with the default Top surface flow being set to 1.00) it is much better than what your pic’s show. With a bit of “confirmation bias”, I believe I can also feel a slight layer time effect between the initial bridging layer and that top surface, but it is quite minor.
Key differences between my print and the 3mf above: Material:
PLA Basic versus PLA Matte: Always assume PLA Matte to be moist straight out of the bag. Even PLA Basic should ideally be self-dried. Values I reset to defaults: Print temps:
Cooling parameters are a box of Pandora, requiring a very good understanding of the different interactions and a systematic approach. You are easily looking at 3 digit test matrices here, even when testing one dedicated theory at a time. There are other, less troublesome means available for troubleshooting (in particular speed and layer height). Strength:
I changed the infill pattern to 5% Honeycomb. Not because it does anything differently. I just prefer Honeycomb over Gyroid. Speed:
I did not understand why the Top surface speed was increased beyond its default. So I lowered it to its default 200mm/s.
Despite using an uncleaned Smooth PEI, there was only very minor warping right at the edges. Nothing to really complain about. Chamber temp was between 38 and 41°C (hot day today).
Wow, Incredible! Thank you for the test. Yours looks fantastic. Pretty much everything I changed away from default was a result of something I read on a forum post somewhere, or a video about speed, cooling, temperature, etc. There was a reason / method behind all my madness, but in the end it might have been just that. Madness. Regardless, I will start with the basics then. I will dry the snot out of my filament. I have been very fastidious with keeping my filaments dry, vacuum sealed, and in close proximity to copious amounts of desiccant due to my abysmal living/printing conditions in the southern United States. However, that does not mean that my filament did not get “wet”. So I will begin there. I will then do as you have done and reset all the parameters back to their defaults and give it another science. If my results remain the same I will try what Bullocks had suggested and go with some thicker walls and see if that shores everything up. Thank you again sincerely for your efforts. I hope to not make them all in vain and get my machine to produce similar results!
I have also finished my enclosure and am currently holding a stable 77F (25C) work environment.
We have all been there The trouble is in priorizing the different items. And not just for newcomers. Posts from different topics or videos about specific trials make it very difficult to assess what is actually important or applicable in any particular case.
Usually, if the basics moisture, plate adhesion, printer maintenance and calibration (machine and filament) are taken care off, the vast majority of issues are covered.
Nevertheless, things like that Benchy Hull line referenced above are still interesting problems.
Well, it probably has nothing to do with how you store your filament. The main problem is that those plastic bags filament usually comes in do not stop moisture. They only slow it down. And after an extended sea voyage, the only safe assumption is that new rolls are always wet. With filament moisture requiring heat to leave the filament, dry storage is unfortunately not enough.
Furthermore, any “special” filament, like Matte, Wood, Glow, Metal/Silk, non-PLA reacts much more sensitively to Moisture.
I am quite impressed how quickly you got that set up and running Respect
A little anecdote from my own, early attempts at battling warping. With PETG at the time (2018?) on a first gen Tevo Tarantula bedslinger. Since I had read about warping being countered by higher “chamber” temps, I told my wife that I was experimenting with the heat curve of the central heating in our (at the time) new house. And that things were rather complicated so that I needed to understand the interrelations between sensors and settings. So we had to have 30+°C in the bedroom in order to have the living room at 24° in winter . She is still cursing about our heating . The best thing: Looking back, I am convinced it was just that my filament was wet .
Thank you for your inspiring words. I will keep at this…I reprinted the baseplate again…with all the settings changed back to what they were (i.e. stock settings). It printed…the…exact…same…way…
I dried the filament for a little over 12 hours. That should have been plenty, the hygrometer read 12% humidity when I pulled it.
I have a few other things I need to print before I get back to this. Next on the docket will be making the walls thicker. I really think that this matte PLA just does NOT want to printed this broad…or some such. Unfortunately matte PLA and PETG is all I have at the moment, and I really don’t want to use my PETG for this.
Regardless, thank you so much for at least proving it CAN be done. When I get back to printing these…and I will…I will post my findings. Also, my wife and I got a good chuckle from your temperature “experiment” story. Thank you again!
& 
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The trouble is in priorizing the different items. And not just for newcomers. Posts from different topics or videos about specific trials make it very difficult to assess what is actually important or applicable in any particular case.
Respect 
. The best thing: Looking back, I am convinced it was just that my filament was wet 