Not flat bottom!

Bambu Lab A1 Series Troubleshooting
1

Hi there, on my A1 whenever I’m doing prints with a significant bottom surface area I always seem to get the bottom curling up…

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It looks like it is going to be good then as the more layers are added it starts to pull the edges up.

Happens with most filaments. I have tried lowering the cooling but doesn’t seem to change anything…

Cheers

2

As the filament cools, it shrinks. For high/long sides, it can pull the part from the bed. If you need to prevent that, then you have to reduce the shrinkage effect. You can also try to fix the base more firmly to the bed. The fixing part can be achieved by changing the bed material, using an adhesive on the bed, changing the filament material, using a brim/raft/ mouse ears, changing orientation of the object, adjusting bed temperature.

To reduce the shrinkage forces, redesign the object if possible - e.g. break up the slab sides with holes, re-orientate the object, print in smaller sections, change chamber/room temperature.

The basics, like clean build plate, dry filament, calibration, no draughts and so on, are required for every print.

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3

Thanks, a few more things for me to try there :+1:t3:

4

Would turn the aux fan off for the first ~10-20 layers, big prints love to peel up.

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5

(cough) the A1 doesn’t have an Aux fan…

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6

Whoops didn’t realize it was an A1… getting my own next month. Maybe close your window lol.

7

Things to try:

  1. Clean the build plate really well, hot soap and water, dry it, and keep your fingers off the surface. This really does help.
  2. Add a brim via the slicer. I’ve got a few models that like to warp, and adding a brim minimized or eliminated it. If you use Orca Slicer, add mouse ears.
  3. Minimize drafts around your printer, With large parts, you want cooling to happen slowly and evenly.
  4. Get a smooth PEI (high temp) plate or an aftermarket plate (I have a Wham Bam PEX plate) These have much higher adhesion.
  5. Pre-heat the bed. Before sending the print, tell the printer to bring the bed up to the target temp (typically 65C for PLA, 70C for PETG) and once it reaches temp, let it sit that way for 15 minutes or more. This allows the temperature to stabilize on ALL areas of the bed. It’s not uncommon for the edges and corners of the bed to be five degrees or more cooler until the bed stabilizes.
  6. On a case-by-case basis, change the cooling/fan parameters. In the filament profiles, on the cooling tab, Increase the “No cooling for the first” X layers, or decrease the fan speeds. Note, you can be more or less aggressive with this depending on the specific model. Parts with overhangs need cooling. Parts with heavy bases may not need cooling for more initial layers, etc…
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8

@JonRaymond previously mentioned about making the brim with 0 model-brim gap if the standard brim gap isn’t good enough. I have printed a few models that benefitted from that approach. I normally use the standard gap, but if it fails, or if I suspect it will fail based on the model, I go with 0 gap. It also eliminates or at least reduces the lines you can sometimes get between a base and vertical walls.

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9

The interesting thing is that there still is a small gap even with 0 model-brim gap because the standard Bambu setting has .15mm Elephant foot compensation.

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