When printing with ABS, I get under-extrusion as soon as I raise the bed temperature to 110°C. If I lower the bed temperature back to 100°C, the under-extrusion issue disappears.
I observe a similar behavior with PLA as well. For example, if I increase the bed temperature from 55°C to 65°C, under-extrusion occurs while the bed is heating up to the new temperature. I especially notice this during the first layer.
This makes me suspect that there might be a power-related issue, either with my printer specifically or possibly with P2S printers in general, where increased bed power draw affects extrusion performance.
I’ve attached two photos for reference.
In the first photo, the print was done entirely at 110°C bed temperature, and it shows severe under-extrusion throughout.
In the second photo, I started the print at 100°C, then increased the bed temperature to 110°C, and later lowered it back to 100°C. You can see the temperature changes labeled on the print, and the extrusion quality clearly improves again once the bed temperature is reduced.
I tested ABS with bed temperatures of 80°C, 90°C, 100°C, and 110°C, and I get under-extrusion at all of them. The higher the bed temperature, the worse the issue becomes.
Whenever I turn off the bed heating, everything immediately goes back to normal.
I also ran tests with white PLA (photos attached). At 55°C bed temperature, everything prints normally, but as soon as I increase the bed temperature to 65°C, under-extrusion starts instantly.
Additionally, I tested blue ABS starting at 80°C, where slight under-extrusion appeared. I then increased the bed temperature to 110°C, and while the temperature was rising toward 110°C, the extrusion quality became much worse. Once the bed reached 110°C, I lowered it back to 80°C, and during the cooldown phase, extrusion was perfect.
However, as soon as the bed reached 80°C again and the heater started PWM activity, the under-extrusion issue returned.
This strongly suggests that the problem is directly related to bed heating power draw / PWM activity, rather than material or slicer settings.
Is there anyone who can help test this? It doesn’t matter whether you use PLA, PETG, or ABS. I’m sharing a sample file below.
During the first layer print, after a certain portion is printed, could you please increase the bed temperature by 10–15°C and see if the same issue occurs on your machine?
Hi, I have the exact same issue. My first layer is terribly underextruded, same as the rest of the model. I also noticed that the extrusion got much worse when I manually increase the build plate temperature. I am currently in contact with support, going back and forth for weeks, even swapping the extruder gears and the extruder motor, but nothing helped. However, after reading here that it maybe has something to do with the build plate heating up, I tested it with Matte PLA from Bambu Lab, and the moment the heated bed kicks in, the printer starts heavily underextruding!
I measured my wall outlet voltage this morning using a wattmeter, and it is reading 226V. When the printer’s heated bed is active and heating, the power consumption is around 1000–1200W. Once the bed temperature stabilizes, power consumption drops to around 300–400W.
If there were a general power supply issue, the printer would not be able to draw over 1000W in the first place. Therefore, it does not make sense that an under-extrusion issue would occur while printing ABS at a 110°C bed temperature when power consumption is only around 400W. During active heating, the printer draws over 1000W without any issues, yet under-extrusion occurs while printing ABS when the bed is stabilized at 110°C and consuming much less power. As soon as the heated bed is turned off, the problem completely disappears.
I am the owner of a company that develops electronic and software products. Based on my experience, I suspect this issue may be related to EMI. It seems possible that the heated bed’s electrical noise filtering is insufficient, causing interference on the servo signals. Alternatively, if the heated bed operates on AC power, the PSU generating DC power may not be able to supply sufficient current while the bed is active, leading to a power-related issue.
Over the entire weekend, I spent a lot of time troubleshooting the printer and tried many different things. The entire extruder assembly was inspected, and the hotend was replaced with a brand-new one. The printer was factory reset. The firmware was downgraded to the initial version, followed by another factory reset. All calibration procedures were performed, including high-temperature bed calibration.
The power outlet the printer is connected to was changed, and I also tested it using the power cable from my A1 printer. I tested with multiple different filaments as well. However, none of these made a difference, which further confirms that the issue is not related to the extruder, hotend, filament, firmware, or calibration. This is because as soon as the heated bed is turned off, everything returns to normal.
I can reproduce something similar on my H2D on 120V. In the other thread we switched to a vase mode cylinder instead of the 1st layer test as it made it easier to experiment and objectively reproducible. It seems likely it is the same effect on both as having 2 models with weird extrusion-rate coupling to the bed heater seems unlikely.
The lack of hysteresis is odd, which seems to make purely thermal explanations unlikely, but in my experiments the magnitude and direction of the effect seems to be coupled with plate location, which suggests a thermo/mechanical flexing.
I believe someone else in suggested that it might be some kind of unusual magnetic coupling between the bed heater and plate magnets, I haven’t investigated this, but it would explain the instantaneous nature.
In other words what appears to you to be under extrusion can also be explained by the plate moving further away in Z. In vase mode this is easier to see as the layers get spread further apart for Z movement, whereas the width changes for an extrusion rate change. In your single layer test it is more difficult to separate these two effects.
I tried your test with two different filaments. I got the same result. One filament actually had a good first layer but once I turned off heated bed it extruded more and was over extruding. because that one filament actually looked good with heated bed on and I am getting under extrusion on most of my filaments I wonder if the issue can be solved with a setting change. Yes the bed being on or off changes extrusion rate or maybe printer adjusts z offset to compensate for the thermal expansion of the bed when heat is on, in any case that shouldn’t limit us from being able to adjust a setting to increase extrusion rate of the filament. did you notice if other layers were under extruding. I thought it was just first layer at first cause my prints look pretty good overall but I noticed other layers with large flat parts were under extruding as well so I think the whole print is under extruding, meaning it doesn’t seem like a z offset issue for me. I also have had a little bit of stringing and looking at some of the first prints I did on that printer they actually are nearly perfect on first layer and no stringing. hm I guess I should do a cold pull now that I think about it.
We opened support tickets both personally and through our distributor (MetatechTR). We received a faster response for the ticket opened via the distributor. It turns out that the MC board needs to be replaced, and a new MC board is currently on the way. I will continue to share updates here.
Yes, actually I’ve been trying to calibrate the filament flow rate for about a day now. However, I had to set the flow ratio to 1.05 for the first layer, and then I started getting over-extrusion on the upper layers. So there is definitely an issue — I can’t get consistent results. Also, when I first bought the printer, I didn’t have this problem at all. I’m attaching the result of an ABS first-layer test print I did back then, which was printed with a 0.95 flow ratio using the default settings.
Through the ticket I opened myself, Bambu Lab has been continuously asking me to try new and unrelated tests, effectively delaying the process. Despite repeatedly explaining that my ABS prints were fine when I first purchased the printer, that I am now experiencing under-extrusion, and that I clearly observed extrusion changes correlated with bed temperature behavior, I am still receiving responses that do not directly address the actual issue.
In contrast, the ticket opened through the distributor resulted very quickly in a conclusion that the MC board needs to be replaced. This inconsistency in handling the same problem is unfortunately a very poor experience.
The new MC board arrived and I’ve installed it. I can now print ABS at 110°C without any under-extrusion issues. However, I still notice that if I increase or decrease the bed temperature during a print, the extrusion changes. While the bed temperature is rising, it tends to show under-extrusion.
I’m not sure whether this is something specific to my printer or a general behavior. If you could test this on your machine and share your experience, I’d really appreciate it.
I never had any problems with ASA on the P1S and now I have printed ASA on my P2S.
The first layer had underextrusion and I just found the topic here by chance. Seems to describe exactly my problem. If I find time, I will perform tests with different temperatures than 100°.
I’m having under extrusion problems too. I only just found this thread. I’m printing Polymaker ASA at 105c bed on P2S (bottom) and P1S at 100C (Top)
I’ll try the P2S at 100c see if it makes a different. I’m really annoyed with the P2S. It’s fine with PLA and PETG. But this ASA has been a nightmare. I got it for my Etsy business, so I could print stuff twice as fast, First layer results have ruined anything that needs a smooth surface printed face down for show.
