Guys, i have been racking my head trying to figre out whats going on. I have been pricinting this model alot now in the past week i have this issue where the top 5 layers are pushing out over the wall.
The filament is PETG Bambu Black.
thickness is 0.16
Im running 3 walls
nozzle temp is at 260 (was 265 but turned it down to see if there is a differnce)
As you can see by the picture is overhanging the walls. Can someone please help we work through this.
are you sure is not from the model!? If not looks like a layer shift check from the other side if getting inside to confirm and check model slicing
But Layer shift can happen from many reasons
On top of my head slicing options try “Ovoid Crossing walls” in the slicer
Then mechanical could be from bad cable management to the head , to belt tensions, unaligned belt leaders - check the maintenance and alignment procedures
not relevant but in the past some Firmware versions also had problems
EDIT: if not from the model and everywhere is outside shifted 360, there is a potential cases of strange warp unlikely with PETG but you never know - change the infill type and rotate 45 degree the model or and change the infill direction and change the infill density
EDIT2: After @EnoTheThracian comment , what is your print speed for 0.16 you should be probably bellow 100mm/S maximum PETG speed is around 140-150 and that is at 0.2 and internal , external max 70mm/S
Looks like classic warping to me, with the overhang showing the first of the top layers? The top seems to print OK as it has a much longer layer time than the walls?
To avoid the shrink-in effect of the wall during printing, you’ll need to reduce printing speed and/or layer height. Be decisive and use 50%. That’ll also help in keeping the higher nozzle temp and hence good layer adhesion.
Can you provide some pics from the slicer preview please ?
In particular one showing the layer speeds and flow rates.
If it is NOT the model, like this top part having a different wall design I bet you find changes in the above pics right where you have the issue.
The shift just is too much to be caused by any filament properties.
If the slicer preview shows a clean wall try to switch fro classic to Arachne and to a print.
I doubt though this will be issue here.
OMG i think you are onto it. I never even thought of sjhrink only expansion. I dont think its the top expanding but the lower walls shrinking in. I have sped things up alittle in my profile and this just may be the casue. Ill test it and let you know the outcome.
I ussulayy print walls at 100 but have lifted it to 150.
yep i think as @EnoTheThracian said its the speed causing shrinking of the lower layers. I am going to slow it all down and run a test. Ill provide feedback here.
Hi its not a shift and not the model. I think its printing the lower walls too fast casing shinkage and then printing the top layers at the correct width. Ill let you know my findings when i test the next print
Great do not forget about infills if you use according to last comment, as the infill can pull the walls in the shrinkage and btw it aways shrinks never expands
What did you change to what? Infill, speed, layer height?
Also, you can loose the skirt and replace it with a close brim for better bed adhesion. And of course, make sure the bed is clean (water + dish cleaner).
A couple of things that haven’t been mentioned so far. For the purposes of ruling out the obvious.
While these next troubleshooting steps may be obvious, they are simply to rule out the obvious. BTW, I am assuming you know how to cut a model into sections, but it is still worth mentioning that for speed of testing and reduction of filament waste, it would be a good idea to cut out the section that is showing this artifact for two purposes: first, to reduce the model print time and isolate the test area; second, to allow for multiple tests on the same build plate, thus increasing test efficiency.
Have you tried flipping the model so that the top is now the bottom? While I fully realize that there are features on the top surface of your model, we are looking to see if the model behaves the same way at those top three layers if they are printed first. Likewise, can we reproduce that effect at the top using a flipped model. You will have to use the rotate and move command to sink the model below the plate to get that test corner to be flush. For example, use a flipped LEGO block and move the pegs below the surface.
To rule out a problem with the model itself, have you tried changing the number of vertices in the model? Use the right-click simplify feature to create two models: in one, increase the number of vertices; in the other, decrease them. If there is a flaw in the STL, this may reveal it by changing the vertices connections.
Regarding the model itself, have you tried converting it to another format, such as STEP, and then re-importing it? Many overlook that STEP files have more precision. Here’s an online utility I use, which is fairly straightforward. Although this utility will only convert the STL into a STEP mesh file, the conversion process will recalculate all the mesh vertices, like taking something apart and putting it back together again. Converting the mesh into another format can also help test the integrity of the model. STL to STEP Converter Online - AnyConv
What happens when you use another filament? This is to simply to rule out filament as a contributing factor.
Are you using the Bambu Default profiles and have you tried the Generic PETG? Again, to rule out filament settings as a contributing factor.
@AK-WA can you share a few more photos on the failed on top and on each side, and if always at the same height. And alco check if the model is not detaching from the plate or actually if the plate is not lifting as if really bad warping can lift the whole plate from the magnets.
And if you not a problem can you share the model , you can use makerworld or any other shared cloud space . I can give it a go later today or tomorrow and give more details
EDIT: Sorry i did not see the photos
Yes it looks like a warping at a glance but also not sure it may be from the model or the photo K/Flow may be still a bit off - but flow looks good , but i guess you tired different infills and rotate the infill or the model to 45degrees
Not sure if you want to share the model for testing…
So I tried on my machine with some red PETG and printed a little box for a friend.
No shrinkage of any concern.
Tried again but raised the bottom to allow for 8mm of gyroid infill - no shrinking of concern.
As you rule out the model and basically the print settings as well I am a bit lost here…
If shrinkage of this magnitude would be your problem those lower wall parts could not be as vertical as they are.
Layer shift does not go all around the model in all different outside directions either.
As before I still would like to see a proper slicer preview if you are unhappy about uploading the model for further checks.
This shift is too even and too defined to be an accident.
