Printing With Lightweight PLA (LW-PLA) - Part 3: Other Settings

Bambu Lab X1 Series
1

And finally the last Part …

In Part 2 we looked at the most important settings for printing with LW-PLA - Nozzle Temp, Flow Ratio, and Speed (aka Max Volumetric Speed). That got me to a really good looking test print. But I started noticing some flaws …

Even though the Eclipson files minimize seams, the seams that remained were really visible and were creating “loops” in the filament. When the seams were on the outside of the print (if I set the Seam Position to “Back”) it created a very visible ridge of filament extrusion. If I moved the seams inside the print (using “Nearest” or “Aligned”), the seams would sometimes print the extra material in critical mechanical areas. If you look closely at the Slicer output, you can see that seams force a retraction and Z Hop (the default Z Hop Type is “Spiral” which creates the loops). And LW-PLA hates retractions and Z Hops! So I went into the Filament Settings > Setting Overrides and set Retraction Length to 0 to disable it (which also disables Z Hop When Retracting). Or you can try minimal Retraction Length (0.5mm) and no Z Hop When Retracting - honestly I didn’t notice a difference. No more messy extra extrusion at seams! I still recommend trying different Seam Position settings on your models and looking at the slicer output to make sure seams are as “hidden” in non-critical places as possible. Here are a couple of “Before & After” Seam pics [LW-PLA - Seam Printing - Album on Imgur]

Well with no retraction, first layer printing is a mess as you can imagine! First layer printing (including brims and the pre-printed border lines) cause “blobbing” and stringing. But none of that really interferes with the actual printing once it starts to build up from the first layer. And LW-PLA is really going to do that anyway even with Retraction enabled!

Finally, let’s close this out and recap some other settings and printing tips:

  • I didn’t touch any of the Cooling settings - they are all left at Default. I haven’t seen any issues with bridging or overhangs.
  • Just a reminder that I also haven’t changed any of the Speed settings. As long as I set the Max Volumetric Speed at 5, I can just let the X1C run on the default Standard settings.
  • For tall, thin, single perimeter models like these plane files, they really need a Brim to add adhesion and rigidity. I am using a 5mm Brim with a 0.1mm Brim Object Gap. I haven’t had any print failures and the Brims detach easily. I’m printing on a Wham Bam PEX build plate and get excellent adhesion with no assistance (no glue stick, etc.).
  • Most of LW-PLA advice I saw (at least for plane prints) recommended setting the Wall Generator to “Classic” and not using Arachne. I use Classic for my LW-PLA printing.
  • You cannot run Flow Calibration before printing on LW-PLA at your “expansion” Nozzle temp. The printer will attempt to adjust the flow for the “expanded” filament height. I honestly don’t know if Flow Calibration is necessary at all using the calibrated print settings (maybe someone can weigh in on this), but I decided to “play it safe”. I changed the filament settings to lower the Nozzle temp down to 190C and ran my test print with Flow Calibration turned on. That would print the Calibration filament in an “un-foamed” state. I let it print long enough to lay down and analyze the calibration pattern and then stopped the print. I figured this would “capture” the flow calibration for the filament before expansion and save it in the printer settings. It’s probably totally unnecessary …
  • There is one weird setting change that is required to print the Eclipson files. A lot of the internal structures are drawn using very small dimensions and they “disappear” during slicing. The “Slice Gap Closing Radius” has to be set to 0 under the Quality settings to get these to work. Also be aware that some design files (notably 3DLabPrint) require using the “Even-Odd” Slicing Mode under Special Modes.

Here is the actual Eclipson print “in progress” using the final settings [LW-PLA Eclipson Model S "In Progress" - Album on Imgur]

And if you want to see my actual Filament and Slicer settings you can go here [LW-PLA - Filament & Slicer Settings - Album on Imgur]

Sorry this is so long! I want to stress again that all of this has just been based on my personal experience, and it represents my “simplified” approach to printing with LW-PLA (specifically for model planes). Like everything else with 3D printing, there are always a lot of different ways to do something and not just one “right” way. I welcome any and all comments and advice and definitely need you to point out any mistakes or errors I have made. I also really appreciate all the information that has been posted on the subject of LW-PLA from people who are a lot smarter than me - I couldn’t even have gotten started without you!

13 Likes
2

Your experience with LW-PLA is really usefull to me. I’ll earn time when I’ll try this filament

Thank you

1 Like
3

Here are the links to the other 2 parts …
Part 1: Printing With Lightweight PLA (LW-PLA) - Part 1: Filament Comparison - #3 by RickNC
Part 2: Printing With Lightweight PLA (LW-PLA) - Part 2: Key Printer Settings - #2 by RickNC

1 Like
4

This tip helped sort out a problem I was having on the Shark Aero model, but I’m still having issues with various STLs being split from the thin geometry. Looks like the non-manifold geometry is causing it but if I make it manifold, I lose the internal geometry. Have you run into that before?

5

Unfortunately I haven’t. I’ve probably been lucky that the models I’ve printed have been pretty well optimized for non-retraction / z-hop printing. I did run into some poor adjacency adhesions, but it turned out to be a flow ratio that was too low. Sorry I couldn’t be more help …

1 Like
6

I followed along and I get a part that looks decent but it seems pretty squishy. Is LW-PLA supposed to be so much softer then PLA?

7

I don’t find that the filament is “squishier” so much as that most aircraft designs only print with one perimeter (like vase mode) with minimum internal structure. The goal is minimal weight, so the parts are mostly air. For me at least the actual LW-PLA shell actually feels kind of brittle. What kind of model are you printing? RC

8

I’m printing the Eclipson Model T. With inland Tough PLA it’s pretty stiff, with ColorFabb LW PLA it’s very squishy. Can’t imagine how it would hold up in flight.

9

That’s pretty strange. I printed my Eclipson Model S using the ColorFabb LW-PLA and it’s structurally very rigid. The skin can be deformed by pressing on it, but it doesn’t puncture easily and there still seems to be quite a bit of structural strength to it. My Eclipson parts cannot be easily twisted or flexed and the skin is rigid enough to “drum on”. However it is definitely more “fragile” than conventional PLA.

My first guess might be extrusion flow rate and layer adhesion? Can you cause the layers to separate or cause the skin to separate from the internal rib structure by twisting or deforming it? Does the skin look solid with no voids? During some of my early testing when I had the Flow Ratio set too low I would get poorly formed prints with very poor structural strength adhesion. Sorry I’m kind of guessing here …

Unfortunately the only way I found to determine the optimal flow ratio and volumetric speed for expansion and dimensional accuracy was to work the Prusa calibration process. LW-PLA is a very different animal from conventional PLA … in my experience.

10

I just received my Bambu Lab printer and have been enjoying your article. My Colorfabb LW-PLA arrives tomorrow. I’ve been trying to figure out how to add your settings as a profile. It would appear that is what you did. How did you accomplish that? Thanks!

11

Thanks for the manual, so far it is printing nicely on my X1C

I did have a lot more foaming and even lowered the temp from te optimum foam temp and decreased the flow ration. I have now the temp at 26 with a flow ratio of 0.4 with a wall thinkness of .67 mm (recommended by 3Dlabprint), the weight of the parts is much lower than indicated in the manual, is this something to be concerned about or is it a good thing?

12

Hello,

I am using PLA Aero. Used Bambu Lab’s PLA Aero for Eclipson Airplanes. Their recommendation is to ensure line width is 0.58mm on a 0.4mm nozzle.

I’ve printed around 15 test tubes and found the sweet spot (it will vary by batch and how dry it is):

Load Bambu Lab PLA Aero profile then edit and create new custom profile and adjust:

Edit extruder profile (choose your 0.4mm profile) and change:
Extruder tab:
Layer Height Min: 0.08
Layer Height Max: 0.28
Retraction Length 0.2
Deselect Retraction when layer change (this allows wiping across the print cuz extruder will still bleed foaming PLA)

Change PLA Aero Filament profile (assuming you want 0.25mm layer height):
Flow Ratio: 0.56
Temperature Initial Layer: 230
Temperature Other Layer: 230
(Plate temperatures, leave as-is, adhesion is so good on Cool Plate)
Max Volumetic speed: 6

Cooling
Min and Max at 30
Layer time at 80
Aux fan speed 20

Now lastly, Process section, please refer to Bambu Lab PLA Aero RC airplane article for all the changes then do this:
Layer height 0.28 (first line)
Layer height (follow Eclipson’s instructions for each model)
Line width section, keep them defaults tuned by Bambu Lab

Add 3mm Brim… Yes they’re super easy to peel off. Surprisedly.

In summary,
I printed using PLA Aero profile by Bambu Lab. Problem: blob random spew once every 50 lines (thankfully only sit outside of wall which you can pry it off and wall remain perfect condition). Its line width was staggering 0.70mm at 0.25mm layer height.

Then I reprinted the plane again, but this time, I followed Eclipson’s recommendation by 0.58mm width so that’s the new tunes… and absolutely no blobs. Insanely improved and weight saving is less significantly but still strong.

Very, very important: Turn off first layer inspection. Because you need to be there to inspect first layer… After it does 2nd layer, you can leave it printing unattended.

When it does purge line, push away blob before it finishes purge line by using your tweezer. This prevents extruder picking it up and bringing it to print area.

Happy printing!

13

There’s no wrong answer. It’s all about density/weight of your goal.

I printed 15 cubes and to test layer separating. They each have different level of force before separation.

I found that Bambu Lab’s profile for PLA Aero to be HARD to break layer bond even only one wall.

Density/weight will depend what project you’re making.

14

Would like to share my new update, I am throwing away my recent parameter changes. I realize Bambu Lab’s recommendations are sooooo much better.

Decided to re-print the whole set for Eclipsion Helix fixed wing It’s 0.72mm thickness (even they specifically want thickness to be 0.58mm). Maybe use sanding tool to enlarge holes for spars for aileron a little. so they don’t become stiff for the servos to work harder.

Happy Printing!

15

Thanks for the tips!

17

Hi kibbycabbit, I am still fighting with the LW-PLA setup from Bambu and the aircraft print from Eclipson.

Would it be possible to share printscreens of your setup for both the filament and the print profile that works for you? I am getting pretty desperate… lots of ruined filament and still not good results :confused:

Thank you
Jakub

18

@RickNC Thanks for your posts, but I’d like to add one thing to consider. I’ve found that the “Max fan speed threshold” affects wall thickness with test cube prints. If you were to lower the fan speed from 100% to something like 30%, getting a thicker wall is possible. I surmise this is because the filament cools slower and continues to expand after it leaves the nozzle.

My rudimentary pull tests with my fingers show that the layer adhesion is still decent with the lower fan speed.

19

I know this is a fairly old thread now but as a newbie, I’m curious as to whether the settings mentioned would apply when using the A1 printer?