10 Common 3D Printing Problems and Fixes

Most 3D printing problems are easier to fix once you know what caused them. A failed first layer, lifted corners, stringing, blobs, gaps, nozzle clogs or a spaghetti print can look serious, but the fix is often a small change to Z-offset, temperature, retraction, speed, flow or filament condition.

This troubleshooting guide covers the most common FDM 3D printing issues, why they happen and what to adjust first. For best results, change one setting at a time, run a small test print and keep notes of what improves the result.

3D Printing Problems at a Glance

1. Poor Bed Adhesion

Poor bed adhesion means the first layer does not stick evenly to the build surface. The print may slide, curl, lift at the edges or fail within the first few minutes.

Why it happens

• The nozzle is too far from the build plate, so the filament is not pressed down properly.
• The build plate has dust, grease or fingerprints on it.
• The bed temperature is too low for the filament.
• The first-layer speed is too fast.

How to fix it

• Clean the build plate with isopropyl alcohol and handle it by the edges.
• Re-run bed levelling and adjust Z-offset in small 0.05 mm steps.
• Slow the first layer to around 15–30 mm/s.
• Use the correct bed temperature: PLA 50–60°C, PETG 70–85°C, TPU 30–60°C and ABS 90–110°C.
• Use a textured PEI plate or add a brim for models with small contact areas.

For a deeper first-layer setup guide, read Creality UK’s 3D printer bed levelling guide.

2. Warping

Warping happens when the corners or edges of a print lift from the bed as the material cools and shrinks. It is common on large, flat models and materials such as ABS, PETG and ASA.

Why it happens

• The print cools unevenly.
• The bed temperature is too low or unstable.
• The model has a wide flat base without a brim.
• Open-frame printers are exposed to draughts or room temperature changes.

How to fix it

• Raise the bed temperature in small steps.
• Add a 5–10 mm brim in the slicer.
• Reduce or turn off part cooling for the first few layers.
• Use an enclosure for ABS or other warp-prone materials.
• Keep the printer away from windows, fans and air conditioning.

If you mainly print ABS, this ABS print speed and enclosure guide explains how temperature, cooling and speed affect stronger prints.

3. Stringing

Stringing appears as thin strands of filament between separate parts of a model. It is usually caused by molten filament oozing from the nozzle during travel moves.

Why it happens

• The nozzle temperature is too high.
• Retraction distance or speed is too low.
• The filament has absorbed moisture.
• The nozzle is dirty, worn or partially clogged.

How to fix it

• Lower nozzle temperature in 5°C steps and run a stringing test.
• Enable retraction in your slicer.
• Start with 0.8–2 mm retraction for direct-drive extruders and 4–6 mm for Bowden extruders.
• Dry filament before printing, especially PETG, TPU and nylon.
• Clean the nozzle tip and check for partial blockage.

For more detail, see the UK guide: 3D printing stringing fixes.

4. Under-Extrusion

Under-extrusion means the printer is not pushing out enough filament. You may see gaps between lines, weak walls, missing layers or rough surfaces.

Why it happens

• The nozzle is partially clogged.
• The nozzle temperature is too low.
• The print speed is too high for the hotend.
• The flow rate is too low.
• The spool is tangled or the filament path has too much resistance.

How to fix it

• Clean the nozzle or perform a cold pull.
• Increase nozzle temperature in 5°C steps.
• Reduce print speed and check whether extrusion becomes stable.
• Calibrate flow rate and E-steps if required.
• Check the extruder gear, PTFE tube and filament path.

5. Over-Extrusion

Over-extrusion happens when too much filament is pushed through the nozzle. The print may show blobs, rough walls, poor details and parts that are too large to fit properly.

Why it happens

• The slicer flow rate is too high.
• The filament diameter is set incorrectly.
• The nozzle temperature is too high, making the filament too runny.

How to fix it

• Print a single-wall test cube and measure wall thickness with callipers.
• Reduce flow rate in 2–3% steps.
• Measure the real filament diameter and update the slicer profile.
• Lower nozzle temperature by 5°C if surfaces look swollen or glossy.

6. Layer Separation

Layer separation happens when layers do not bond properly. The model may look complete but break apart along the layer lines.

Why it happens

• The nozzle temperature is too low for good layer bonding.
• The print speed is too high.
• The layer height is too tall for the nozzle size.
• Cooling is too strong, especially on functional parts.

How to fix it

• Increase nozzle temperature in 5°C steps.
• Reduce print speed by 15–20%.
• Keep layer height below about 75% of nozzle diameter.
• Reduce part cooling for PETG, ABS and other materials that need stronger layer bonding.

7. Clogged Nozzle

A clogged nozzle can stop extrusion completely or cause weak, uneven flow. It often appears after long print sessions, high-temperature printing or material changes.

Why it happens

• Burnt filament or carbonised residue builds up inside the nozzle.
• Dust enters the hotend with the filament.
• The printing temperature is too low for the material.
• Abrasive filament has worn the nozzle opening.

How to fix it

• Heat the nozzle and remove visible residue with a brass brush.
• Use a cleaning needle carefully to clear the nozzle tip.
• Try a cold pull at around 90–100°C, depending on filament type.
• Replace the nozzle if flow does not recover after cleaning.

8. Elephant Foot

Elephant foot is when the bottom layers spread wider than the rest of the print. It can stop parts fitting together and reduce dimensional accuracy.

Why it happens

• The nozzle is too close to the bed.
• The bed temperature is too high.
• The first layer is over-compressed.
• The model weight presses down on soft lower layers.

How to fix it

• Raise Z-offset in small 0.05 mm steps.
• Lower bed temperature by 5°C and test again.
• Enable elephant foot compensation in your slicer.
• Use a small chamfer on the bottom edge of functional parts.

9. Spaghetti or Mid-Print Failure

A spaghetti failure happens when the model comes loose but the printer keeps extruding filament into the air. It wastes time and material, especially on long prints.

Why it happens

• The part loses bed adhesion during the print.
• The model is tall, narrow or easy to knock over.
• The print speed is too high for the shape.
• There is no filament runout or failure detection.

How to fix it

• Clean the build plate and confirm Z-offset before long prints.
• Add a brim for tall or narrow models.
• Slow down prints over 100 mm tall.
• Use filament runout detection and AI failure detection where available.
• Check that the printer is on a stable surface.

10. Inconsistent Extrusion

Inconsistent extrusion creates random thin and thick lines across the model. Unlike under-extrusion, the problem is not always constant; flow changes during the print.

Why it happens

• The filament is damp.
• The spool is tangled or pulling unevenly.
• Extruder gears are worn, dirty or too tight.
• The nozzle has a partial clog.

How to fix it

• Dry filament before use and store it in a sealed box with desiccant.
• Check the spool path and respool tangled filament.
• Inspect the extruder gear teeth and clean out filament dust.
• Clean or replace the nozzle if the issue continues.

Conclusion

Do not change every setting at once. Start with the most likely cause, make one adjustment, then run a small test. Most 3D printing problems can be solved by checking the first layer, temperature, retraction, flow, speed and filament condition in a clear order.