Hello everyone!. Brand new X1c user here (just got it a couple of days ago), with an issue on an arched/domed object. Before getting my printer, I had a friend printing prototypes on his P1S with the exact same flaw
The object is getting this weird flaw right at the top of the arch. The flaw gets worse when using adaptive layers, but is still somewhat visible as a “ghost” when not using it.
The flaw appears on both sides, but opposite each other (doesn’t happen on both sides of the arch)
like this
Using x1c with standard bambu pla, standard settings. The object is imported as a 3mf file from Plasticity.
Thanks for any insights
In the slicers preview, are there feature visible that match the defects?
(Scarf) seams, low flow regions, speed changes, near (not neccessarily exactly at) fan speed changes, starting from layers where slow down commands (slow down for overhangs, max fan speed min layer tume) take effect?
And of course, is the filament dried and calibrated for both flow and pressure advance?
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Hi EnoTheThracian, thanks for responding
None that I can tell, the bad scarring starts right about where the supports meet the model (using tree, auto), but you can see some (without breaking the skin of the model) a little below that. No seams in that area. I have other parts on the bed that print without issues, it is just this particular model.
It roughly seems to match the area where adaptive layers begin, but like I mentioned, it is still faintly visible in the exact same spot when not using adaptive layers.
The settings are are all the default for .12mm high quality, except for the enablement of supports. Printing at different quality settings doesn’t change the outcome
I had printed other different versions of this same model (shorter) using STL (instead of 3mf), so I’m wondering if it might be something in the format of this particular one, and if changing the format might not fix the issue
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Hi @bsteagall ,
That already tells us something as it eliminates seam settings from the troubleshooting.
For further indications, change the preview from “line type” to “flow”, “speed”, “fan” and “flow” by clicking on the header to open the drop down.
From the error pic, I’d expect a flow (control) or fan induced problem.
So dry and PA-calibrated filament is important with improvements possible by looking more closely at slowing commands and trying to keep a more or less constant flow.
From that original pic, I doubt that it is related to the data file format. But then, being a hammer/materials guy, all I see are nails/material & processes issues 
Best wishes,
Eno
Hi Eno
Ok, I looked at flow, speed and fan, nothing looks out of the ordinary
flow
speed
fan
I’m going to do the flow dynamics and flow rate auto calibrations on my filaments (wasn’t aware that this could help, not with a brand new printer and using bambu filaments)
I’ll report with results
Thank you Eno
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Well, there are some speed and hence flow changes where the supports come up when compared to the lower layers. They do seem to be smaller than the defect pic shows, but it is difficult to judge from thebpics alone.
When you do the Pressure Advance calibration, you’ll see that defects used for calibration bear quite a resemblance to the error pic. No smoking gun of course, but, well, an indication.
Before you do the calibrations though, please dry your filament. It has probably been on an extended sea voyage and those bags only slow down water uptake. They do not prevent it. Maybe that alone is enough to resolve the issue.
Best wishes, 
& 
,
Eno
PS:
Hey Eno
Yes, put all the filament through a 12 hr drying cycle on the AMS2, so got that covered already.
thanks for all the help…
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ok, dried all filament (shows at 10% humidity in the ams). Performed the separate automatic flow dynamics and flow rate calibrations for each of the filaments (a couple of times on different days, just to make sure I did this right, being a newbie with this printer).
Tried different quality settings, up to .08 extra fine
No significant change, and now having used
3 different types of filament (Pla Basic, pla matte and pla wood) and two separate printers (p1s from a friend and my x1c), I don’t think it is a material issue (at least the odds seem to point that way). I guess I could do the manual calibrations, but I’m not sure they would help (but I could be wrong)
I also don’t think it is variable layer height, as it is still visible when not being used (just not an ugly scar, although on the pla wood it was)
I don’t think speed is an issue either, as it already shows that in the area where the flaw occurs, it is printing at the slowest rate.
hmm, I could change the orientation of the model, but because it is an arch with a channel inside, I’d rather not deal with supports when I don’t have to.
I’m going to cut into one of these when I get home, see how far the scar goes into the model
I do find the position of the scars interesting, the most visible ones are located where the yellow circles are, while almost completely gone from where there’s an x, and roughly at the same height as the supports
Thoughts?
ok, looking at some other parts of this bed that are also having issues, which I believe are interrelated (as they all happen at the support contact layer)
and when changing orientation to avoid this (using a different filament)
Its like the immediate layers a little before and after are just junk
On all these prints I’m using the .08 mm high quality setting.
I have tested using the PLA/PETG support filament as the interface, and besides wasting a lot of filament and time, did not correct this either.
I’ve been looking at some of the other posts regarding bad surfaces after supports, spheres and what not, but nothing so far gives me a definite solution
Hi Eno
Ok, I printed out a model without supports, and although the bridge was too far (and therefore sagged), this definitely points to the problem being how BS (how appropriate no?) handles them
with supports (doesn’t matter what type, for this one I used standard)
Without
Seems like overall the quality of the skin is better too (or is it my imagination)
Not sure what settings could fix this. I’m at the latest version of Studio, latest firmware on the x1c. Is there a more “recommended” version of Studio and firmware that I could backtrack to? (after reading all the posts about issues with firmware, I’m wondering if this is not related)
Should I try a different slicer?
Mhm, tricky. I have certainly seen new versions of BS loosing information and doing things differently. Especially with the 2.0 update as it had many, many changes for the H2D without them being able to test everything. So the last version before that is probably worth a try. Or Orca slicer. But you’ll need to print in developer mode. Well worth the added functionalities though.
I am not sure if that will solve the issue though. I usually use PETG interfaces with PLA (and vice versa) with a 0mm top z-surface. That takes care of sagging which may actually be a root cause here.
I have not come across this issue myself, but there are a few ideas.
For example, the “slow down for overhangs” potentially slowing down too much for large overhang conditions and the speed change being applied rapidly could explain why typical PA or sagging effects occur at these locations away from the seams. Using 50mm/s for all angles has been reported to be beneficial.
Similarly, there’s the option to inverse outer wall direction with every layer which may help to smooth things and provide further diagnostics.
While I am not certain if it would improve or worsen your print, playing with the wall printing order would lead to different results. The default inner/outer does appear the best approach for this though.
Finally, can you post a layer time preview? With PLA, I do not expect issues from that but you never know.
Similarly, your speed preview shows velocity changes in the troublesome area. Can you zoom in on them, compare both sides (the good and the ugly) and indicate printing direction? If defects occur on the side opposite the seam and there’s a sudden speed change, setting a single “slow down for overhangs” speed and smoothing acceleration would be a likely remedy.
And of course: observe printing closely. When battling the original PETG Basic settings, I noticed overhangs also altering fan settings. But the latency of the fan spinning up and down was not implemented in the slicer at the time, leading to no effects where it mattered and overcooling where it mattered…
&
Hey Eno
I think I’ve figured it out, after looking at what it was doing in that area, saw that the speed goes from 10 to 350 in the direction of the scars
The nozzle goes from super slow to blazing fast.
I’m going to add a modifier to test, but i think this might be the problem… I’ll report back
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Hey @bsteagall ,
Excellent 
That is due to the “slow down for overhangs” speeding up to the outer wall speed. It is not a factor on the other side as that is probably still in the seam vicinity and hence accounted for better.
There is an option to smooth acceleration in these instances. You may need to enable Studios “Advanced” or “Developer” mode in the Preferences.
&
Hey Eno
I want to thank you for all the help, You were patient and gave me the insight needed to fix this issue, I really appreciate it
One last question, would you have any recommendations on how to make the bottom sides of spheres better? My model uses a ball and socket (sphere attached to a bar)
You can see in some of the previous pictures how those turned out, and although for this model I came up with a solution that somewhat works (the sphere was filleted to a tear shape), and the speed changes have made them better, I would like to use the original full sphere (for articulation and mobility).
I know spheres are inherently difficult to 3d print, but even when using sacrificial meshes, the bottom layers still look basically unfinished. The sphere is rather small (10mm)
Do you think the smallest layer height together with slower speed in just that area would help? (in general, my plate is sliced at .12 preset)
thanks again
Bryan
Always a pleasure 
Sphere’s are really an overhang/sagging issue rather than something where layer height may help.
And I admit that your solution (starting with a fillet before transitioning into a sphere) is one of my go-to’s.
The other is the use of supports with a dedicated interface material and 0mm distance. For PLA, I use PETG or (in very rare cases) BVOH. For PETG, I use PLA. But is does require an AMS since best quality is achieved with adaptive layers.
Best wishes,
Yours,
Eno
