Large object PLA warping
I'm essentially printing a large (wdh=20x10x5cm) hollow box (2mm thick walls) with rounded corners (10mm radius) on the sides. The issue is that the corners are warping despite various efforts.
My setup is as follows.
- Prusa i3 MK3 inside the IKEA Lack enclosure
- White PLA filament
- Original Smooth PEI sheet
- Default 'Generic PLA' settings at 0.30mm layer height
I've tried the following already.
- Increased bed temperature to 70 °C
- Decreased bed temperature to 50 °C
- Washed the smooth PEI sheet with soap (which increased adhesion tremendously)
- Used a (large) brim
- Used a 3mm tall raft
After printing about 10mm in height the corners start to slowly warp upwards about 2mm. My best guess is that is has to do with tensions between hotter (near buildplate) and cooler layers (on top).
I would really appreciate to hear about your experiences and things you'd do to solve this problem. Thank you in advance.
RE: Large object PLA warping
IMHO a clean bed surface should be sufficient for most prints, but as you note when you have large prints your bed adhesion has to be able to compensate for the pull of upper layers. If a good clean surface isn't getting the job done, you may need to apply some glue stick. Angus from Maker's Muse has a video about prepping his surface to improve adhesion.
Cheers
-Bob
Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit
RE: Large object PLA warping
Large, rectangular objects are tough and prone to warping. You've pretty much done everything I would do. One last step is to add something like Layerneer bed weld, plus brim. But I have one model in production right now that sometimes even then gives me issues as it actually pulls the sheet off the heat bed in the corners... (binder clips help).
RE: Large object PLA warping
I was printing a 20x20x8cm box recently and ran into the same problem. Using glue stick helped but it wasn’t perfect. A friend of mine later suggested to use painter’s masking tape on the bed first and use a raft. I haven’t tried that but thought I’d pass it on.
if anyone has tried this, I would love to know if it worked.
RE: Large object PLA warping
I did some further investigation and experimentation. It seems that the internal tension between layers slowly builds up when more layers are added. At some point this tension becomes stronger than the bed adhesion which results in warping. Increasing bed adhesion essentially delays this problem by a factor, to possibly after the print is finished. For me washing the smooth PEI sheet with soap and adding a wide (15mm) two-layer (0.6mm) brim (using cylinders in PrusaSlicer or using Fusion360) did the trick for me. Note that this does require additional effort in removing the brim with a sharp knife later.
A few final notes.
- The brim that can be added in PrusaSlicer wasn't strong enough.
- Glue sticks might definitely be a good way to further increase bed adhesion.
- In my opinion the smooth PEI sheet has much better adhesion with PLA than the textured sheet.
- I occasionally use soap to rejuvenate my sheet. Properly using IPA with a clean paper when the bed has cooled down after each print doesn't preserve bed adhesion over time.
RE: Large object PLA warping
Take care when using glue stick, too much is just as bad as too little. Take a look at this:
Cheers
-Bob
Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit