3D Printing Problems: Causes and Fixes

Almost every failed print with filament comes down to a few causes: the first layer, temperature, moisture, cooling and the material itself. This guide goes through the most common 3D printing problems and tells you what to check first depending on the filament you use.

Warping: corners lift off the bed

Plastic shrinks as it cools. If the base of the part cools faster than the rest, the stresses pull the corners off the bed. It is the classic problem of ABS, ASA, nylon and polycarbonate.

• Print engineering materials in an enclosed printer with no drafts.
• Use the bed temperature from the material's datasheet and clean the surface with isopropyl alcohol.
• Add a brim and round off sharp corners in the design.
• Reduce the part cooling fan on the first layers.

Stringing between parts of the print

These are thin strands of plastic that cross the gaps. They appear when material oozes from the nozzle during travel moves. PETG and TPU are the most prone.

• Dry the filament: moisture multiplies the strings. The times are in the guide on how to dry filament.
• Lower the nozzle temperature toward the low end of the datasheet range.
• Tune retraction with a test tower (except on TPU, which handles long retractions poorly).
• Turn on the slicer option to avoid crossing perimeters.

First layer won't stick

• Check the leveling and the distance between nozzle and bed: it is the most frequent cause.
• Clean the bed: the grease from your fingers is enough to stop PLA from sticking.
• Use the bed temperature from the material's datasheet.
• Print the first layer slower and a little thicker.

Elephant's foot

The first layers come out wider than the rest. It is usually caused by a nozzle too close to the bed or a bed that is too hot. Raise the first layer a little, lower the bed by a few degrees or add a small chamfer at the base of the design.

Under-extrusion and gaps in the walls

• Check that the nozzle is not partly clogged or worn, especially if you use abrasive materials such as carbon fiber.
• If you print fast, you may be above the flow your hotend can melt: slow down or raise the temperature.
• Calibrate the material's flow.

Layer separation (delamination)

The bond between layers fails when the plastic reaches the previous layer too cold. Raise the nozzle temperature, reduce the fan and, with engineering materials, close the printer. It is common in ABS and ASA printed in drafts.

Nozzle clogs

• In enclosed printers, PLA can soften too early and clog: print it with the door open.
• Flexible filaments jam in Bowden extruders or with long retractions.
• Filled filaments need nozzles of 0.4 mm or larger.