PLA warping: what to check when corners lift

The first layer looked good. Half an hour later, one corner of the tray is making a break for it. PLA warping that develops during a print needs a different check from filament that never stuck in the first place. Start by noting when the corner lifts.

Separate the start from the later failure

If the first lines move as they are printed, work through the first-layer adhesion checklist first. If the base stays flat for several layers and lifts later, record the layer or elapsed time and the corner involved.

Photograph the model on the bed before removing it. Include its orientation in the picture. “Front-left corner lifted after 20 minutes” is a more useful record than “PLA keeps failing.”

Review the temperature conditions

Plastic contracts as it cools, and that stress can pull a corner free. Check for a nearby vent or open window blowing across the printer. Keep the normal print-cooling fan settings from the correct PLA profile while you investigate; turning off cooling entirely can create other problems.

An enclosure is not an automatic fix for PLA. Follow your printer manufacturer's instructions for PLA ventilation and door or lid position. A setup intended to keep ABS warm may be unsuitable for PLA.

Check contact area

A brim adds material around the base to increase its contact with the plate. Try one on the same model after confirming that the build surface is clean and properly calibrated. Allow for the extra cleanup around the edge. A brim is temporary scaffolding; it does not have to win a beauty contest.

Inspect the sliced preview before printing. Confirm that the base is flat on the plate and that the brim actually touches it. If only a tiny feature contacts the bed, reconsider the orientation or model design.

Use a comparison you can trust

Save the original profile, then repeat the model with one change. Keep a note of the plate, temperatures, brim setting, and room airflow. A small crop of the affected corner can help with a quick test, but it may not reproduce the stresses of the full-size tray.

For HARP PLA+, start within the recommended 190–210°C nozzle and 50–80°C bed ranges, subject to your equipment's limits. See the starting settings guide and Prusa's explanation of warping.