You could try reducing the inner wall line width to 0.42 which may help prevent the outer wall from being pushed out. Or tick the “precise wall” option.
Am trying that now, @RMB. Thanks.
I would be surprised if reducing the inner wall line width would solve this, as I experience no blobs on other layers.
Could it be that too much PLA flows out when the top layers of the base (4 in total) are being printed? Or is it a cooling issue and should cooling be increased?
Update 17:13
No luck. The print comes out similarly.
It would be possible to print layers that first extend too far beyond the body and then are not supported there. This problem could arise if you have too few walls. Then 1 or 2 walls would be printed almost into the air and a ceiling/bridge would be placed over them at a 45° angle, which of course is then also unsupported. Over time the pressure normalises and the only way to find out is to look at the layer construction after it has been cut in Bambu Studio. Similarly, you can look at the temperatures and speeds etc…
So we’re just poking around in the fog and doing a collective guessing game.
Have you tried changing the Quality=> Advanced → Order of inner wall/Outer Wall to Outer?Inner? This will force the GCode to deposit the outer wall first.
Also, check your GCode settings and make sure your Verbose GCode is set to off. This likely will have no effect but there is a YouTube video that performed experiments showing that the CPU on some printers can be overtaxed causing stalls in the depositing of filament but those artifacts typically show as consisted zits on the side, not what you are seeing. But it’s worth a shot.
Here’s that video.
On a long shot, have you checked your internal temperature of your printer? It’s very unlikely but the SOCs used in the Bambulab designs have a thermal throttling feature that will cause the CPU to slow the clock rate to protect from thermal damage. It would produce artifacts but they would be random.
And of course, I assume you tried another filament setting in Orca, correct? If not, play around with using the Generic PLA profile which prints at a lower volumetric speed and see if that has an affect.
Yes that is strange and one of the frustrating things that seem to happen with these printers that don’t happen with others. I believe the issue is with the printing speed. When printing the lower portion which has the infill, the outer wall has time to fully cool but when it first transitions to the next layers, there’s no inner portion, so the walls are being laid very quickly and possibly aren’t cool before the next layer is put down resulting in it being squashed out. After the first couple of layers after the transition, the cooling speeds up and it looks better again. To fix this, you may need to play around with fan speeds. I’m not near my computer to check but I’m not sure if there’s a speed setting to reduce the speed after a certain transition but you can try reducing the outer wall speed down also.
Thanks a lot for the involvement @Olias and @RMB. Very much appreciated!
There is good progress to report.
But first an update on the things I’ve experimented with, without any luck:
- Order of walls: outer wall first.
- Verbose GCode is (and was) checked off
- Change filament setting to Generic PLA, to print with a lower volumetric speed
Things I still have to try:
- Added the following line to the G-code: M413 S0 ;Disable power loss recovery
- Internal temperature of the printer (although I wouldn’t know where to start with this one, tbh)
My guess right now is that this issue has to do with fan speed. As you can see the four top layers of the base have a different fan speed.
After changing the cooling overhang threshold - which is a filament setting in OrcaSlicer - from 50% to 0%, I get the following result:
Finally, as a test, I’ve removed the top shell layers (from 4 to 0) to keep fan speed for outer walls consistent.
Let’s see what happens!
Update 11:06
YES!
Now only need to find a solution to get that top layer back in.
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Great to see you came up with a methodological way of solving the problem! The more info like this that is out there, the better for others that might run into the same issues.
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Nice Sleuthing. 
And thanks for taking the time to circle back and share your findings. I learned something here and would never have thought to check fan speed as a possible culprit but it now makes sense. BTW: If you might share that STL file and configuration file, I’d love to see if the results can be reproduced. Who knows? You may have struck upon another stress test that is not part of the current lineup of tuning parameters. I’d love to see if I can take your model and then change the overhang threshold gradually to see if that line can be moved by changing the threshold in increments. If it does then Viola! we might have struck upon a new diagnostic method.
False alarm!
Back at it, as fan speed doesn’t seem to do it.
It’s the top layer of the base. If I remove the top layers (from 4 to 0), I get a perfect result. Bringing it back - 4, 3, 2, or 1, doesn’t really matter - creates the same blob effect. Even when I lower the outer wall speed to 30 mm/s and fan speed is similar (and ideal) for all layers, I get the blobs.
I’m currently experimenting with smaller line width of top layers, but that doesn’t help coverage of the base and gives an ugly effect.
I’m happy to share the file, but can’t seem to upload a 3FM file.
If you want to share the file, one of the printer repositories such as printables.com, Thingiverse.com or Makerworld.com would be the best choices.
You’ll want to include the STL, the 3MF and also export the config files to an empty folder area so that you can isolate it. You’ll see two .json files. One for the filament and one for the system config. This will allow anyone to reproduce the exact configuration you are currently using. Bear in mind, I have only a P1P which will still produce a valuable test because it will at least allow us to rule out differences in technology.
Hmm, I would look at the extrusion to see if too much material is being pumped. Just lower the extrusion to try it out. In the filament settings.
Does the print warp after the top layer is printed?
SOLVED!
Circling back to you guys, I’ve done the following.
After contacting a construction engineer, he said this [freely translated]:
The cause of the blobs is the flat top surface of the base, which shrinks during cooling down. Therefore, a ‘saucer’-like formation occurs. The edge (outer walls) will therefore rise slightly. The print layer thickness is slightly too small, resulting in too little volume available for the filament wire. Possible solutions are:
1. No top surface - which I’ve stumbled upon myself already
2. Thin base
3. Concave in the base
4. Bulge in the base
5. Annular grooves in bottom
Long story short, I’ve experimented with the 3rd option: the base slopes downwards!
And guess what? Problem solved!
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Awesome research my friend and thanks for sticking through to the end. Too many people just give up. Your findings are not what I would have ever thought of but it all makes sense.
This is well beyond my skill-set but this sounds like a perfect challenge for the authors of the slicer software. I wonder how many other people experienced similar issues only to either just abandon all hope or tried something else like moving the object orientation which obviously wouldn’t work with this geometry.
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Can you show what you changed to fix this? Was out a change in the design of the model to make the vase base interior concave (or convex)?
Thanks, @Olias!
And @RMB, I’ve made changes to the design (in Shapr3D).
As you can see in the attached screenshot below, the base no longer has a straight horizontal line. In addition, I’ve increased the number of top surface layers (and thickness), to make it sufficiently opaque. The result is impressive!
@narna Thanks for the info, I’m glad you figured it out. It’s a pity it wasn’t easily fixed in the slicer settings.
I just got my X1C and I am experiencing the same problem. There is not much help online or on YouTube. Can you show us where and what in the slicer you changed to get this solved. Thank you
Sure @JTP_3D.
This was not a slicer issue, but a faulty design. I used Shapr3D (highly recommended btw) to create an angle in the top surface of the bottom. This prevented shrinkage, as described in my previous comments.
Hope this helps mate!
Thanks for the reply. I was realy hopping to get this solved faste. This is not the case.
Well I am not even shure if this is the same problem. I will upload photos for others to see if this is actualy a blob.