Strange "bubbles" on the border of the print

Bambu Lab P1 Series
1

Hi guys,

I recently upgraded my P1P to a P1S with enclosure and all. Since then, I started seeing some strange “bubbles” on the first layer. They usually form around the edges of the print (not in the middle). I thought, at first, it might have something to do with the increased temperature inside. However, after leaving the door open, the bubbles did not disappear.

IMG_1943
IMG_19431920×1440 248 KB

The print itself continues without problems, the adhesion is fine, and the end result doesn’t really change (although I found some dots in lines further up the model, but only a few).

I went through the wiki page for printing problems, but couldn’t find anything. I am sure somebody here will know the answer right away, but I am kind of at a loss here. Help is appreciated.

Cheers
AnotherGuyver

2

When I see that on the first layer, I’ll usually run flow calibration AND bed leveling. Sometimes I have to do it a few times, but it usually fixes the issue.

3

This filament is being way-over extruded. You need to do a flow calibration. You need to do Pressure Advance calibration.

There are no strange bubbles, here. Just too much filament.

1 Like
4

Ok, so I tried a few different things and still can’t figure it out.

First, I tried the calibration. Picked the number, that looked best, adjusted the values and did it again with almost no change. It went from .98 to .9702 to .9517 and so on. I was getting frustrated, so I just tried out putting in way crazy numbers to see if anything changes at all. The first time I got rid of those “bubbles” was, when I put in .7, which seems crazy low.

Now the first layer was pretty flat, the ones after that a bit janky on the infill, but otherwise fine. Am I missing something? How can it be, that I need to reduce the flow that low to see a change? Before I upgraded to P1S + AMS I never had this problem. Is there another setting for flow ratio, that I am missing? Should I adjust the K value?

Any help is appreciated!

Kind regards,
AnotherGuyver

5

Do you have the build plate set to Textured PEI? If so, the Start GCode sequence has a command that lowers the nozzle slightly to compensate for the bumps of the textured surface. From the looks of it, that sheet is smoother than a textured sheet. If that’s not it, you could try using Orca Slicer and adjust the flow rate down slightly only for the first layer so the rest of the print isn’t underextruded.

6

Yes, I do. However, I have the same problem on the textured PEI plate. (I actually got this plate based on a recommendation, which also said to leave it at the textured plate setting, but you are right, it is much smoother).

7

So another “piece of evidence” I found when printing a part for the respooler.

IMG_1975
IMG_19751920×1555 168 KB

In the beginning it started printing fine, but over time, well, you can see the result. The angle doesn’t change on the model, it just started doing these janky lines… is this also caused by overextrusion, I wonder?

Cheers,
AnotherGuyver

8

You might try supports on that angled surface. The lower portion looks good actually.

9

Yeah, the thing is, the instructions say no support needed and Orca Slicer doesn’t even highlight this as a large overhang, hence the confusion on my part…

10

Clearly though, it does with whatever settings you are using now. You could try adjusting the layer height to see if that helps if you don’t want to add support.

11

Check in the sliced preview using the “fan”, "speed’ and “flow” settings to see if there are changes to those values at the location the print quality deteriorates.

12

I tried printing just this one part (instead of multiple like I did before) and it did increase the quality. I still had one are which was pretty bad, but it’s no comparison how it was before. Apparently, it gets worse the more parts I print simultaneously.

IMG_1976
IMG_19761920×2560 408 KB

13

Ok, thanks for the tip. I tried doing just that and here are the results:

Screenshot 2023-12-20 at 17.59.48
Screenshot 2023-12-20 at 17.59.53
Screenshot 2023-12-20 at 18.00.01

As far as I can see, it stays the same?

14

After adding mass to the printer (i.e. sides, door and such for the upgrade) did you re-run the printer vibration calibration?

What type of filament are you using?

If it’s PETG, slow the print speed down and turn the part cooling fan off in the filament profile and you will always get better results.

The last pic you posted, it looks like it is all happening around the seam. Did you change any seam settings?

15

Yes, I did. Just reran it to be sure. Still the same problem.

I have tried various brands of PLA, but mostly Overture. Now that I am thinking about it, PETG wasn’t half bad. Had some stringing, but definitely better first layer than PLA.

Nope, just reduced the flow a little. But yeah, you are right, it is happening at the seam :confused:

16

Can you post your seam / wipe settings?
It just seems like something is off.

17

So I have a short update on the matter.
I have tried debugging this the best I could and here are the results:

I recalibrated the printer a few times and ran the flow calibration about 5 times. The thing is, just going by the first layer, the -20 one looks almost perfect. No bubbles, nothing, just straight lines. However, since I have to evaluate the end result, 0 always comes out the best, albeit having a horrendous first layer.

IMG_1981
IMG_19811920×1440 328 KB

You can see, the bottom left shows the -20 on the calibration test. The top one in the middle is the 0. I ran the test with 0.98 flow rate and in the end it stayed at 0.98 (maybe with a tendency to 0.9702). No matter how often I did the test, the result for the first layer is always bad, but the top most layer turns out fine and really bad for the -20 square.

IMG_1978
IMG_19781920×1440 463 KB

You can see after the second calibration, on the top layer, 0 looks pretty ok, the other ones don’t.

I was reading up a little more and saw, that the 0.6 nozzle doesn’t seem to have a good profile. So I switched back to the 0.4 nozzle today and tried calibrating it again. Unfortunately, the results were the same.

I then saw, that an Overture PLA profile was added to the official list and tried that out. It turned out to be worse than my custom one (derived from the Bambu Matte PLA), although it does seem better, if I reduce the flow to 0.9702.

I keep thinking it might have to do with speed. The first layer is printed really slowly and creates those ridges on the sides, while the other layers are printed fairly fast. Is that something, that can be fixed with pressure advance? The Overture PLA preset seems to have a flow ratio of 1 out of the box, meaning that the preset must have been good enough.

@Lexi My seam settings are the default ones:
image

Cheers,
AnotherGuyver

18

Don’t take offense to this, but you said you added an enclosure to your P1P. Is your chamber simply too hot for PLA now? I have a P1S and I had to remove the glass and the door or it’ll melt the filament too much and cause overextrusion/flow/heat-creep issues. The fan only blows in one direction so one side will be nicely cooled but the other side furthest away from the fan will melt. From your recent update it looks like it’s always happening on the left side.

19

Yeah, I upgraded to the P1S. I was also thinking about this and followed the advice to leave the door open while printing. Didn’t do much compared to fully closing it. I did a PC print in between (which prints at crazy 290 degrees) with fully closed enclosure and it hat the same first layer. PC prints at a maximum temperature of 310, so I don’t think, I got the inside that hot and still had the “ridges” on the side…

20

Ok, so quite an interesting tidbit of information. I talked to BambuLab support and they suggested changing the first layer line width from 0.5mm to 0.42mm. So this is the default setting in the Overture PLA profile:

image
image766×542 46.9 KB

And this is the changed setting, so the line width is 0.42mm almost everywhere,

image
image754×546 48 KB

I then reduced the flow to 0.9702 and oh my god, the first layer is great and the rest of the result is also pretty good. Even the ironing works well. So that is that. I guess it is the solution to the original question.

However… I am now wondering, why the default settings produce such poor results. I guess the upgrade to the P1S changed the printer properties, but I didn’t expect it to change so much…

1 Like