My print has an ugly and terribly out of tolerance ring around it where one section ends and another starts. I’ve tried every logical to resolve it, I’m stumped. I’ve had nothing but problem using stock profiles.
As you can see from the picture, the outside has a bad bulge on that layer, and it’s absolutely not a feature of the 3D model itself. Even trying all the inner/outer settings changed absolutely nothing.
In this second picture, there seems to be some artifacts on the surface in other areas too, almost like a bump in what should be a flat surface. The seam in the corners also has bad blobs.
First. Thank you for uploading the 3MF and showing such a clear picture. Your post serves as a great example of posing a question the right way because it takes away all of the back and forth guesswork.
What you’re seeing is the filament shrinking at different rates which is why that ridge is showing. Looking at your 3MF, I see that you are already setting you wall order to outer/inner which is where I would have started. You might also try turning on Arachne for the wall generator but that will likely only help in the corners if at all.
However, two things I noticed. First, the Bambu ABS filament profile you’re using does not have pressure advance enabled. I might suggest turning on PA.
You could use the default of 0.02 but I’d suggest using Orca Slicer’s PA calibration utility to dial-in a more accurate pressure advance. PA pattern is quicker but PA Tower is more precise. PA line in my view is useless, that’s what Bambu uses.
The other thing you can try is to increase the wall loops to 4. Right now you have it at 2. The issue here is that there is a stark transition in filament density between your layers which is what causes this kind of ridge. They cool at a different rate. If you increase the wall thickness to 4 or 5. This should make the transition between layer densities less abrupt.
The last thing you might try is to change the speed at which the outer walls are deposited. This will give each wall more time to set up. You have it at 60, so try 30 or 20 just to see if it influences the shrinkage.
Ok, I tried all those suggestions, and while it definitely helped, it didn’t fix the issue completely.
When I look at the layer time, I can see that even when I print the outside wall first, the print time for that layer is extreme compared to the ones below. I’m not sure why printing the perimeter first still causes minor (but definitely visible) bulging. It almost seems like a slicer issue where it’s treating that area differently just because it’s on a layer that also has a top layer.
Could it be that the bulge is cause by non-uniform cooling times? That is, the layer above and below the bulging line are contracting from cooling nearly equally, but that one layer is not shrinking ‘normally’ because it has so much time to cool and doing so quicker because it doesn’t have a hot nozzle depositing new material on top of it?
Yes, because it is what it is, printing outter walls first can only compensate it, not fully solve it. There’s no easy fix for this problem (“benchy hull line”)
I think this is the correct answer. The geometry of the printed part ultimately dictates the flaws, and while I found ways to mitigate it somewhat, there was nothing to prevent it, because in end the end, that layer spends more time cooling than the rest. Also, in my particular case, because one section is terminating its infill, while the outer perimeter is NOT, this results in part of the print on that layer using 100% fan because it’s bridging above he infill before the top layers.
Here’s my tips after 20 prints trying to fix it:
Choose which section you need quality, and try to match that with the other sections in every category (e.g. layer height, layer time, flow, speed, fan%, etc). For me, the exerior was most important, so I matched the troublesome section’s layer specs with the rest of the exterior.
Print that section first (outer/inner for exterior quality, inner/outer for interior quality or tight interior tolerance).
There are likely unchangeable parameters that are likely to cause issues, while you can’t forgo these entirely, try to minimize them. For example, the remaining artifacts are caused by 2 things:
The layer time is longer than layers above or below the ‘hull line’ (bulging area), while this can’t be fixed, I can increase the infill speed to reduce the time, increase the time of the other layers, reduce the number of top layers. This will help close the gap.
The infill bridging layer needs 100% fan to function properly, so this will cause asymmetric cooling and thus different shrinkage on that layer. I set the fan to a fixed percentage for all layers, but infill/overhangs is a separate parameter, and you don’t really want to change that. So all but 1 of my layers are operating at 60% fan speed, the only exception being that bridge/infill layer, where the fan operates at 60% for non-bridging/overhang sections, and 100% for the bridging/overhang sections.
Orca currently has a pr to do something like layer time smoothing, it’s experimental but it’s why full support of orca without the Bambu Connect is important.
