Hello everyone,
I urgently need your help!
I printed the calibration test from Bambu Studio today. Everything was perfect on the front side. But on the right side (see photo) there were strange bulges on the slope. What is the problem?
I used the 0.2mm standard profile with PLA White Matt.
I cleaned everything. I re-tensioned the belts (I hope I did everything right).
The filament was previously dried with the Sunlu S4 for 6 hours at 50 degrees Celsius.
Now I have printed a shovel. Here is the same error on the same page. Why is that? Have I possibly tensioned the belts incorrectly or do I need to replace the nozzle?!
Before you jump into a rabbit hole you might get lost in…
If the belts move freely and mostly in the middle of the tensioner rollers all is fine.
See them rubbing against the top or bottom of the roller and you should align them a bit better - that’s done with great care and those two screw secure the roller in the correct position.
Assuming all is good there…
Certain types of overhangs are a total pain in the behind, like the ‘roof corner’ in the first pic.
Some of it is printed basically mid air with only tiny bits bonding with the previously printed layer/wall, resulting in imperfections at those corner points that keep building up.
Similar story in the second pic - the bonding is not sufficient and the filament gets loose or misplaced on the print.
Possible fixes to try >
Properly calibrate/confirm your flow ratio and after that the k-factor.
Do a test print to determine you max flow rate or go with a low default of under 20 to try.
Hone in on the best nozzle temperature if not done already, no stringing, no oozing and still a strong layer bond.
If you adjusted the nozzle temp check the flow ratio and k-factor again as these three rely on each other.
Now print a simple overhang test model, like just a degree slope and observe when the print starts to struggle.
You can often see how let’s say 35 degrees is still still fine while at 45 the print goes bad without supports or other changes.
The goal is to now to find the best overhand settings, like slowing down or increasing the cooling to drive the still good part as high up in the angle as possible.
You will see that you can only improve things so much, especially once you use test prints with rounded overhangs or rounded slopes.
If things look great at let’s say 42 degrees but start to go off above 46 degrees then start with supports at 40 degrees…
In case of recent Studio,firmware updates or having done a good cleaning and other fixes : ALWAYS perform a full hardware calibration!
Yes, that nasty half an hour so game of the printer rattling around until it sounds as if it falls apart…
Maintenance is a good thing but the calibration your machine still has is based on how things were BEFORE you adjusted or replaced things 
Thank you very much for your answer!
Unfortunately, the self-calibration does not bring any improvement.
What I find really strange is that these problems have suddenly appeared. The prints were perfect before.
And what I find even more strange is that the gradient on picture 1 and the scoop on picture 2 are perfect on the other side of the print. (See these photos here).
How can that be? :-/
If the calibration is good it only leaves a few things …
Like the scarf seam option - if enabled it can make things messy sometimes.
But your model looks too even to suffer from this.
Am I assuming correctly that you print the scoop with this flat bit on the plate?
If so than we are still talking about overhang issues here.
Rounded overhangs are hard to print with great results.
Try with a smaller size to safe filament >
Set three wall loop, inner walls 0.55mm, outer wall as standard.
Reduce the overhang speeds by 25%.
If this gives you a significant improvement try to play with the overhang speeds a bit more.
Only add more wall loops or make the lines thicker if there is no change at all.
Do you get these defects only on the side facing the aux fan? Or is that independent of the part orientation in the chamber? That could point to an issue with the aux fan.
What temps are you seeing in the chamber throughout the print and what are typical ambient temps around the printer? That could explain emerging draft issues.
Did you have a nozzle issue recently? Calibrating a damaged or partially clogged or a nozzle with wrong thermistor readings could lead to colder than expected overextrusion.
