Hello, This problem started recently after I swapped in a 0.6mm nozzle and new extruder gears on my 2-month. old P1S
I am printing Overture Matte PLA with 200, 55 bed temps. Every other setting is the Bambu Studio Preset
There are weird artifacts on (mostly) sharp corners of a print. Bumps (sometimes forming a pattern) run up only on a corner of a print. The first layer flairs out a lot, then tapers in, tapes out, and tapers back in. Each bump/“hole” is about 8 layers tall. To be clear, this happens only on corners, and opposite corners have bumps on the same layer, so this is not some layer shift issue.
Now I am noticing bumps on the infill edge of the first layer (this was after pressure advance calibration)
I have already:
• Run calibration many many times
• Clean and lube z-axis
• Tighten belts
• Rebuilt carriage (just extruder and hot end)
• Ran flow dynamic (pressure advance) calibration, determined 0.015 was the best)
I printed 5 of the same part at a time in 4 corners + center because initially, I thought I had a bed warping issue. I did test prints at 0.18, 0.30, and 0.42 layer heights. As layer heights got wider, so did the bumps.
I can’t find anything on visual troubleshooting guides, and Google searching isn’t turning up results, so can someone help me?
All images are attached here.
Can’t see much of the top surface but it seems to be quite clean.
If it is and also free of gaps try to a proper k-factor calibration.
Do both the pattern and line test if in doubt.
The k-factor affect the acceleration/pressure advance calculations.
Sharp corners mean massive speed changes from fast to almost stop then fast again.
If the -k-factor is a bit off you can get those bumpy corners.
Especially if on those layer heights the overall layer time or such are different.
A temp test might be helpful as well.
As in checking at what temp stringing start and at what temp a thin wall or such starts to turn brittle.
We usually print with a fast speed, for example I print PLA often at over 400mm/sec for the outer walls.
That only works properly if the nozzle temp is cranked up quite a bit.
I print between 225 and 235 with PLA…
Only if the model is too complex, e.g. overhangs and such I use a lower temp and also lower overall print speed.
As for the first layer…
Mine are not always perfect, especially if the first layer is rather thick.
Quite often I compensate by hitting the slow button for the second layer.
The slower speed means those bumps are mostly ironed out rather than the nozzle bumping over them all the time.
Yours though look a bit extreme - no offence!
If you have not done proper flow rate calibration yet then give it a try.
What’s a proper calibration you ask?
Most will tell you do to a case mode print, measure the wall thickness and then calculate the matching value to get a wall as thick as set in the slicer…
That however is only great for SINGLE WALL or vase mode objects and results in an extrusion rate far too high.
Other people suggest to print those patches and then just select the one that looks best to adjust the factor based on the number of the patch…
I like neither…
The standard cube in 3mm hight will do fine and uses next to no material.
Single bottom layer, 15% percent infill, 5 top layer’s and Bob’s your aunty.
Set the infill overlap to just 5% and print the thing.
If there is gaps in the top infill increase the flow ratio, if there is build up reduce it.
The goal is to get it perfectly smooth and fully filled without and gaps between the lines.
Once sorted check by how much you have to increase the infill overlap in order to leave no gaps at the ends of the lines.
Getting teeth on the other wall means reduce it a bit, having gaps where the infill hits the wall means increase the overlap.
If you complete this with a k-factor calibration you should see a huge improvement.
Thank you so much for the detailed reply. 
I’ll try these out tomorrow and report back.
I forgot to mention originally that I did indeed calibrate Pressure Advance and Flow Rates. I got 0.015 and no change respectively.
Just for good measure I went back and recalibrated both, flow rate with your method, and the issue persists.
I am beginning to think this is an issue I can’t fix in the slicer, either my sensors (accelerometer, load cells) are damaged, or there is some issue with the Z axis.
Speaking of Z axis, I am noticing two possible problems:
-
during ABL, my bed stops to adjust almost consistently every time in two areas: marked with red in my drawing:
I am afraid that the red is starting to form a diagonal line through my bed.
I already manually leveled the bed.
-
Whenever I move the Z-axis down, every time at certain points in its travel I can hear the balls in the ball screw fall down the spiral in the ball nut. I don’t know if this is normal, but it has me worried.
Aside from Z axis problems I also see a lot of temperature fluctuations on the bed and nozzle, but usually are only -1°
Check if the bed/plate are crooked or not 
Create a cube covering the entire plate.
Make it just a single layer thick or just stop the print once the infill is done.
If you suspect uneven spots stick with 0.2mm otherwise feel free to go to 0.15 or 0.1 to save some filament.
If there is bed/plate issues you will see it on the infill in the red areas.
Best to set the infill direction to the y direction instead of the default 45 degrees.
The z-axis can collect dirt and filament leftovers.
If they make their way inside the ball areas all things can happen…
There is good models to download to clean those rods and then apply fresh grease without making a total mess.
If you hear rattling balls already it might be worth to take it apart in order to check properly and to clean them out.
If faulty replace.
