Very weird issue popping up all of a sudden. Happens with multiple filaments. Pic is of Sunlu PLA Silk @ 230°C.
I have tried lower/higher temperature and more/less cooling to no effect. These micro-gaps are randomly distributed around the print, but tend to favor certain faces more (regardless of part orientation). Wall order is default (inner-outer-infill). It’s almost like the printer stops extruding for a split second, or the nozzle pressure is too low for a second.
This is NOT the z-seam as it is in a straight vertical line not visible in these pictures.
The filaments have all been dried in a filament drier, down to under 10% RH.
This is NOT the z-seam as it is in a straight vertical line not visible in these pictures.
Just to be clear you are not using a random seam position correct ?
If this is the case then I would check your PTFE tubes and couplers to see if the filament is binding anywhere you could also have slippage in the extruder gears like dirty teeth or the extruder stepper motor is acting up.
Those look a little like the gaps that show up in the max volumetric flow rate calibration test (racetrack) when the flow rate is more than the extuder can keep up with.
What is the max flow rate you have set in the filament profile?
Why are you printing so hot?
What are your speeds?
I have read that silk likes to print a little slower than other PLA.
Flow ratio = 0.98
Temperature is what was recommended for silk PLA in this printer. Have tried down to 215 with no noticeable difference.
Speed is 50mm/s
I’ve seen this issue in some of my prints too. I’m not recommending this setting be completely disabled (like below), but I was able to resolve it by disabling retraction. So, it appears the issue is retraction related.
I will give that a try. It’s weird that it would be retraction related, though, because it’s in the middle of a line as opposed to at the start or end of a new line.
I do a lot of silk printing and I was about to suggest this issue.
I haven’t seen this in person but was in something I read about making silk look better. Silk does an odd shrink thing due to the elastomers that make it shiny. So, it could be a retraction issue.
Again, it might not be, as I’ve only seen similar in photos in the trouble shooting sections lol.
Disabling retraction helps (but not eliminates) this issue, but is basically a non-starter because of the stringing issues it causes.
Interestingly, the issue is hugely improved if the outer line is not printed last. I am not sure how the line order would cause intermittent underextrusion, but here we are.
Did you manage to sort out this problem ?
We have 4 Bambu lab X1 printers and they print great. We just purchased 2 new printers and on both of them we are having this problem. We are using the same Gcodes and the same Filament so the problem must be with the 2 new printers.
Any other suggestions ?
Try swapping the hotends between the new and old printers. Since wipe on retraction seemed to point to it, I suspect BL might have changed mfg ever so slightly on the newer hotends for you to just push it over.
Never was able to fix it. In the areas it was bad, I had the printer print the outer lines last, which dramatically reduced the occurrence. I still don’t understand how the line order would cause underextrusion.
More time to build pressure in the head, probably. I just set all my silks to a .99 or 1.0 flow ratio instead of the default .98, and it seems to have solved most of the issue for me. FWIW.
