Hello guys,
I have a strange line on my print and can’t find a clear reason for it :
I have use the standard PLA print profil from bambu lab (Since it’s a basic PLA from bambu)
And in the profil the only modification are :
And I just put on my P1S the anti vibration feet with a fresh calibration.
What could be responsible for this defect ?
Edit : better picture
The line at the front edge is a purge line.
no the line on the object 
I will put a good picture in 17 min since it’s a little tricky to take a good one with the P1S runing
If you look closely you will see a “discoloration” between the bottom and the top of the print
Definitely need a better picture that you have promised.
Currently, the only line I spot appears to be a reflection of tiles.
Enlarged it looks like a slight layer shift
Edit better picture, you can see now the delimitation
It looks like the change is at the same height as a change in model shape on the opposite side of the model which we cannot clearly see for confirmation.
If the length of the run of filament in loops changes, the orientation of the filament as laid down can change slightly and reflect light differently.
Without seeing the other side of the model, this would be my guess.
Yes the model change shape precisly at that line.
Can i do something about it ?
Can you take a picture with no shadows ?
In Bambu Slicer (BS) slice the model and change the view to speed.
You may well see the speed at the bottom is different to that where the shape changes.
You could then add layer height modifiers, set at those height positions and change the speed for those modifiers to match the bottom or the top depending on which bit is fastest.
Ideally, you are looking to slow down the speed model prints to the average of the whole print.
If the top part is faster than the bottom, slow the top and vice versa.
No change of speed : (Oh i may be spot one when you angle it !)
in Bambu :
New picture for Neiljt (it’s dark here sorry i can’t have picture without shadow…)
That does look similar to a benchy speed change , which if i remember correctly was something to do with the gcode,
best to message the model owner
thanks i will put those image and my question under the file
First of all, to be clear, this isn’t necessarily a “strange line”. It’s sheen changes, which in your case, are likely due to variations in cooling speed and layer times, but not changes in print speed.
You can think of it like this: Imagine you’re driving down a road at a consistent speed of 30 MPH (48.2 KPH), and it takes you roughly 2 minutes to travel 1 mile (1.6 km). If another driver were to start travelling down the same road the second you reached the end of the mile, they would drive over any given segment of the road roughly 2 minutes after you did, giving said segment a 2 minute “cool down” period before another vehicle drives over it. Now, picture a road that is 2 miles (3.2 km) long. Traveling at the same 30 MPH (48.2 KPH) means it takes 4 minutes to get to the end. This creates a longer “cool down” period for any given segment of the road before the next driver travels over it. The only thing that’s changed is the length of the road, not the speed of the vehicles, but this itself results in more time for the road to cool between each pass. It also results in a longer time in general to travel to the end of the road.
In the case of 3D printing, the “road” is each printed layer, and the “drivers” are the extruder nozzle. When the printer extrudes material while travelling at a constant speed, the layer it’s currently extruding (aka the layer directly beneath the nozzle) is still hot. The longer the extruder has to travel before it’s able to lay down the next layer (go over any given segment of a layer again), the more time the previous layer has to cool. This is why a longer travel path, even at the same speed, results in more cooling time for the previous layer. This difference in cooling times can lead to sheen changes in your print, which is what you’re seeing.
All this comes down to increased layer times, which results in differences in cooling times in different areas of the print. This is what I think is likely the cause. However, unfortunately, I’m not experienced enough in BambuStudio or OrcaSlicer to know a potential solution to how you could make this more even. But I wouldn’t consider this anything super problematic or worrisome, because it can be fixed in the slicer and isn’t a hardware issue.
I sliced the model you’re using myself (I’ve printed it as well, so I remember what it is). Notice if you select “Layer Time” in the slicer preview, you’ll notice the changes line up with the changes you see on your printed model.
so if i understand it correctly if i slow down all the printing those demarcation should disappear since the cooling will be more “average” through all the printing.
Printing in silent mode would probably slove it.
I will need to find a way to have a good average through all the model when i want to make a good looking print. (I guess slow is your friend)
if i extrapolate on my next print i will be able to see where the demarcation should occurre.
find a request on github :
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