Hi friends. I’m very new to printing and I’ve been chasing an issue I’m wondering if anyone can offer me some insight on. I recently got a Bambu X2D and I’m having consistent issues with surface quality on a part I’m trying to print. It’s been hard for me to chase down what exactly is happening here, but from the research I’ve done I think it’s a shrinking problem?
It seems to only really happen on layers with those hole features or where there’s a support interface on the rear of the object.
Printer Information:
Printer - Bambu X2D w/ AMS 2 Pro
Filament - Bambu PLA Tough+
Profile - 0.12mm High Quality
Nozzle - Stock 0.4
Build Plate - Cool Plate Super Tack
Steps I’ve Tried:
- Dried filament
- Changed from inner/outer to inner/outer/inner
- Rerun initial printer calibrations
- Calibrated filament for FA and Flow Rate
- Lowered nozzle temp from 145 to 140
- Tried printing with the lid off and door cracked open
- Cleaned build plate
- Cleaned and lubed all rods and screws
- Tightened belts
- Slowed outer wall speeds to ~40 mm/s and checked “slow down for overhangs”
- Currently trying Arachne walls instead since it’s a thin part
Settings after steps:
Factor K - 0.035
Flow ratio - 0.9781
Nozzle temp - 240°C
Heatbed temp - 40°C
Chamber temp is holding at ~28°C with lid on and door closed, 25°C when open
Outer Wall - 40 mm/s
Inner Wall - 100 mm/s
Part Cooling Fan - 100% after 1st layer
Retraction Length - 0.4 mm
Any ideas or help here would be much appreciated! Thanks so much.
Very unlikely this is a shrinking problem.
It looks to me like the rapid start stop to do those narrow sections aren’t getting enough time to build proper nozzle pressure, so it’s getting under-extruded.
Have you done a pressure advance calibration?
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Could be cooling. Set the view to show layer time, and see if you can see where it matches up with the horizontal lines on the print. In that case, adjust the minimum layer time so that the ffilament is heated and cooled more evenly.
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In addition to the good advice so far I think some/most of the same ideas may apply (even though it’s a different printer and filament): Repeated part artifact, printing in petg
I’ve had the same issues with PLA T+ (and others) as shown here and described in the linked thread. Even the “quality” preset profiles aren’t always tuned perfectly (for what one is printing).
I like cutting “tricky” bits out into their own smaller model and testing settings that way until I’m happy. But gotta watch that layer time and cooling to make sure it’ll match the full model when it comes time to print that.
-Max
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I did a manual PA pattern calibration on it and ended up with a K Factor of 0.035. Default setting on the printer was only 0.026 so at first I thought that seemed like a really big jump, but it does seem better than where I started. Didn’t solve the issue, though. Did a manual flow rate calibration as well.
I’ll take a look at that!
I’ll take a look at that article, thanks for sending it!
I would suggest going to the slicer and looking at the previews (layer time, fan, line width, etc.) and see if there are any previews that show an identical artifact area. Odds are if one does, it is likely the best place to start looking for a problem.
For example if the layer time preview shows color changes in the same place as the issues on the print, I would try to even out the layer times with the cooling max layer thresholds section in the filament profile.
So, just scroll though the previews and see if something stands out or looks related to the problem areas.
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Yeah I think you guys are on to something with the preview showing the issue. Especially in Layer Time, there’s a change in color that almost exactly mirrors the artifacts on the print. I’m currently now just picking my way through articles trying to learn what to do about it.
Actually, this may be the culprit.
The area where those holes are is cranking all the way down to 10 mm/s, and the parts where it shows that almost exactly match the artifacts on the print. I’m not really sure how I can counteract that, though, as that’s a 100% overhang. I assume it needs that extra time to cool down and not fail.
I don’t think it’s the part cooling fan thresholds, as the fan is cranking at 100% pretty much throughout.
In my experience it’s not so much the slowing down (for bridges/overhangs) that’s the issue, it’s the acceleration / rapid speed increase afterwards. It ends up over- or under-extruding at that point. Lowering the other speed/accel. settings (like walls, not bridges/overhangs) or speeding up the bridge/overhang a bit seems to help, and that Smooth speed discontinuity area I mentioned in other thread – minimizes the overall change. Or playing with bridge flow settings, as others have suggested (I’ve yet to try that).
Anyway, I think you’re on the right track to diagnose it. Make sure to scroll the layers down to those horizontal slits and examine the speeds/etc. from the “top” as well.
-Max
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Yes! I’ve adjusted the discontinuity setting and I’m about to run a test print with it, we’ll see if that helps. If that does the trick itself, great. If not I’ll look more into diagnosing and adjusting the accelerations.
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The slow down for the overhang is likely causing the layers to shrink slightly and that manifests as the artifact line (kinda like the Benchy bow/hull line).
The smoothing of the speed discontinuity may actually help. As I would think if you can even out some of the speed differences, the lines may improve enough to not be noticeable.
Another fix could be to make the speed changes gradual. That can be done with speed modifiers or maybe even better, layer height gradients. For example, set the overhang layers to .12mm in the variable layer height widget and then click the “Smooth” button to apply a gradient.
Another option would be to add supports so the printer can just buzz through the sections. That would actually improve the quality of the overhangs and bridges (see the looping edges falling on each overhang). Also they should be fairly easy to remove.
*Also, remember… you don’t have to reprint the whole thing. Tune by section. Cut the section you want to tune, apply the settings and see how that section turns out. Quick fast tuning.
First, I want to thank everybody for the incredible responses so far! This sort of thing was exactly what I was hoping for when I made this post.
Here’s the results of the first test chunk of that problem area. This one only had the smooth coefficient and Arachne walls applied. To my eye it seems a bit better for sure, but still evident. So I’m going to keep poking at it. I’m about to start another test with Variable Layer Height applied, and if it’s still not there I’ll do another with supports.
If anybody wants a closer look at what’s going on with settings, or has an abundance of time to fiddle, I’m going to attach the .3mf of the chunk I’ve made to troubleshoot this.
Trouble Test.3mf (175.3 KB)
