PEI Sheet for Bed Adhesion

[clough42]

So there are a ton of factors with warping.

1. how close to the edge of the bed you print. (more warp)
2. How evenly the heat bed heats (check temps in corners vs center)
3. If its an enclosed environment to retain said heat.
4. Size of part - Larger parts will warp more.
5. Infill percentage of the part (more infill, more cooling plastic to pull on corners)
6. What you are using to adhere part to bed.
7. Temperature of the bed.

I found with large parts, with a fair amount of infill (15% +) I create a custom brim. I use 123d design and create 20mm strips to match up to the sides of my part and make them .4mm in height (2 layers) then i import them along with my part in to simplify3d and line them up overlapping the main part (on the same plane) by a few mm. This fixes the issue of the part still curling at the brim point (the point of a brim in the slicer is to have it easily removed). Ive found this works very very well.

Also the geometry of the part. Parts with long, straight filament strands between 5 and 10mm up off the bed warp a lot as the long strands cool and pull on the corners. Parts with holes that break up those long strands stay flatter.

Here's an example of a part (not mine) with holes that break up all of the long strands.