I’m having surface quality issues printing regular Bambu PLA, with Bambu Support for PLA from the left head for support - bad lines / ‘gappyness’ missing in certain layers of vertical external walls. (as you can see)
When I print temp towers with either head on its own, they actually come out nearly perfect. Also, as you can see in last pic, when I print just PLA, without using separate head/material for support, the problems are greatly reduced. (although still that weird diagonal/vertical groove which is not in the design!)
Is it likely caused by the temp of the heads being affected on the layers where it switches between heads?
You can also see crappy noodle-ing of the Support for PLA material in small spaces. (although when I use it solely to print a full temp tower, it comes out really nice!)
Current humidity in AMS is 30% - do you think humidity is likely the issue? Run more regular drying to fix?
that line on the bottom is likely your seam, you can confirm it in the slicer’s preview panel. The seam looks particularly messy but seam is a seam, you’ll have one somewhere.
support for PLA is notoriously sensitive to moisture, make sure that spool has spent at least a 6 hour session actively drying
What is your pressure advance / flow dynamics / k factor for this gray filament? I dont follow the newly released machines well enough to give direct advice, but I would say you need a different value than what it is using right now, or to slow down the speeds. Dry also might not hurt.
You’re correct, moved to random seam, looks much nicer.
Yep just re-running the dryer now - also going to try regular PETG as alternative to ‘Support for PLA’ some recommend.
I’ve only ever used auto for these settings (or Bambu defaults for the filament) so hadn’t been modifying settings. But I’m running the Flow Dynamics Calibration now, which outputs its recommended values for these… will see what the test looks like.
Thanks for suggestions!
Factor K comes out as 0.04 from auto calibrate procedure. And in the manual calibrate, 0.035-0.04 show the nicest (straight, consistent) results, so suspect that’s a good setting.
Even if you have two heads, one is still “resting” for some amount of time while the other is printing, so it needs to be “primed” to make sure that the filament inside is freshly extruded.
If you’ve ever used a frosting bag, imagine how the frosting in the tip gets kind of hard and crusty once you leave the bag out a bit, and how you wouldn’t immediately just start frosting again but would want to get that bit out.
That setup increases temps not just for the PETG nozzle but all around - for PLA nozzle and bed as well. So all runs pretty hot, but seems to work well. Extra heat on bed seemed to make glue unnecessary?
I use PETG for both the support/raft base, and the support/raft interfaces. In my models that makes it easier to remove all the support as one component, and avoids the extra interfaces. (out of left nozzle)
Drying/humidity particularly important for PETG, I try to keep the AMS HT I have feeding left nozzle below 20% humidity, and run for a few hrs beforehand if possible.
Speed probably matters. Or in this case, going slow especially for the interfacing. I have small parts, so running most speed settings at 100-180mms range. But super slow 30mm/s for Support interface.
(yet to go back and check if I could bump those up now other fixes are helping though)
The actual structure of the support is always best if it’s ‘tuned’ to the model. So for instance in my parts, I have some heavily enclosed layers, where removing the support is difficult without damaging the model.
So in that case I’m using:
normal, ‘Snug’ support structure
50% initial layer density
Rectilinear Base pattern, easily to remove these ‘noodles’ from one side, wide pattern spacing of 4-5mm
Bottom interface layer of 0mm, easier to remove and didn’t really need a flat interface on the bottom. Top interface layer still needs 2 layers for smooth supported surface.
But I’d tune those very differently for a more sparse or organic print…
