In this guide · Part 6 of 7
Key takeaways
- A clean build plate, a correct first layer and dry filament fix most filament printing problems.
- Change one thing at a time and re-print a small test, so you know what made the difference.
- Most resin failures come down to levelling, supports, print angle, room temperature or a worn FEP film.
- Simple, regular maintenance prevents many problems before they start.
How to troubleshoot a failed 3D print
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Work out when it failed
A failure on the first layer, partway through or only in the finish points to different causes. Keep the failed print, because it's useful evidence.
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Check the basics first
Check that the build plate is clean, the bed is level (or the Z-offset is right), the material is dry, the spool turns freely and you're using the correct slicer profile.
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Change one thing at a time
Adjust a single setting, then print a small test part. Changing several things at once makes it impossible to know what worked.
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Ask for help
Still stuck? Send our team a photo of the print with your printer model and material.
Filament (FDM) printing problems
The print won't stick to the bed
Likely causes: a dirty or greasy build plate, the nozzle set too high, the wrong bed temperature or a worn build surface.
How to fix it: Clean the bed with IPA, re-level or lower the Z-offset slightly, and use the bed temperature for your material. Add a brim, and use a glue stick or adhesive for tricky materials. Replace worn build plates.
The corners lift or curl (warping)
Likely causes: the plastic shrinking as it cools, often because of draughts, a cold room or a bed that's too cool.
How to fix it: Add a brim, keep the printer out of draughts and check the bed temperature. Print ABS, ASA and nylon in an enclosed printer.
Fine hairs between parts (stringing)
Likely causes: damp filament, a nozzle that's too hot, or retraction settings that don't suit the material.
How to fix it: Dry the filament first, because this solves most stringing. Then lower the nozzle temperature in small steps and use your slicer's material profile, which includes tuned retraction settings.
Gaps, thin walls or missing layers (under-extrusion)
Likely causes: a partly blocked nozzle, damp filament, a temperature that's too low, a tangled spool or a worn extruder gear.
How to fix it: Check that the spool turns freely, dry the filament, raise the temperature slightly, and clean or replace the nozzle (nozzles). Check the extruder gear for ground-up filament.
Nothing comes out, or the extruder clicks
Likely causes: the nozzle too close to the bed on the first layer, a clogged nozzle, a temperature that's too low for the material, or a tangle.
How to fix it: Raise the Z-offset slightly and check the temperature. To clear a clog, heat the nozzle and push filament through by hand, try a cold pull, or fit a new nozzle.
The layers have shifted sideways
Likely causes: the print or printer was knocked, a belt is loose, something is blocking movement, or the nozzle caught on a curled edge.
How to fix it: Check that the belts are firm, the moving parts run freely and nothing is in the way. Fix any curling so the nozzle can't catch the print.
Layers split or crack apart
Likely causes: printing too cool, cooling too strong for the material, or draughts. This is common with ABS and ASA.
How to fix it: Raise the nozzle temperature a little, reduce the part-cooling fan for heat-resistant materials, and use an enclosure.
A tangled mess of plastic (spaghetti)
Likely causes: the print came loose from the bed, or part of the model was printed in mid-air without support.
How to fix it: Fix the bed adhesion first, then turn on supports in your slicer, or rotate the model so it needs fewer.
Droopy overhangs and saggy bridges
Likely causes: steep overhangs without support, too little cooling, or a nozzle that's too hot.
How to fix it: Turn on supports for overhangs steeper than about 45°, make sure the part-cooling fan is working, and try rotating the model.
A flared bottom edge (elephant's foot)
Likely causes: a first layer squashed too much, or a bed that's too hot.
How to fix it: Raise the Z-offset slightly or lower the bed temperature a little. Many slicers also have a setting to compensate for it.
Resin printing problems
Nothing on the build plate, or the print stuck to the film
Likely causes: a build plate that isn't level, too little bottom-layer exposure, a cold room or a dirty plate.
How to fix it: Re-level and clean the build plate, warm the room to a comfortable temperature, and increase the bottom-layer exposure slightly, following the resin manufacturer's guidance.
Parts broken off or missing sections
Likely causes: too few or too thin supports, a poor print angle, or a worn or damaged FEP film.
How to fix it: Add more or heavier supports, tilt the model at an angle, and check the FEP film for dents or cloudiness. Replace it if needed (FEP films).
Layers separating (delamination)
Likely causes: the print moving between layers, exposure that's too low, or resin that hasn't been mixed well.
How to fix it: Shake the resin well, check that the build plate and vat are firmly tightened, and increase the normal exposure slightly.
The print is still sticky after curing
Likely causes: the print wasn't washed thoroughly, the cleaning liquid is dirty, or it hasn't been cured for long enough.
How to fix it: Wash it again in fresh cleaning liquid, let it dry fully, then cure it again.
Cracks, or hollow models splitting
Likely causes: resin trapped inside hollow models, or over-curing.
How to fix it: Add drain holes to hollow models so uncured resin can escape, and follow the recommended curing time.
Prints keep failing in the same spot
Likely causes: a damaged area of FEP film, or a fault on the printer's screen.
How to fix it: Check the FEP film over the light, and use your printer's screen test (exposure test) to check the screen. Contact us if you think the screen is faulty.
How to maintain a 3D printer
| How often | Filament (FDM) printer | Resin printer |
|---|---|---|
| Before every print | Wipe the build plate with IPA. Check the spool turns freely. | Check the FEP film and vat are clean and undamaged. Shake the resin. |
| Every few weeks | Check the belts are firm. Clean dust and plastic from the moving parts and extruder gear. | Filter the resin to remove cured bits. Clean the build plate and wipe the vat. |
| Every few months | Inspect the nozzle and build surface for wear. Check screws and frame are tight. | Inspect the FEP film and replace it if it's cloudy or scratched. Check the screen protector. |
| Whenever offered | Install firmware, app and slicer updates from your printer's manufacturer. | |
Keep a few spares to hand: nozzles, FDM build plates, FEP films and cleaning and maintenance supplies. For brand-specific parts, browse parts and upgrades.
Frequently asked questions
Why does my 3D print always fail at the same height?
On a filament printer, check for a tangle or snag on the spool, a loose belt or something catching on the moving parts at that height. Also look at the model in the slicer preview, because a sudden overhang or small contact area at that point is a common cause. On a resin printer, look for a weak support or a sudden large cross-section.
How do I unclog a 3D printer nozzle?
Heat the nozzle to printing temperature and push filament through by hand. If that doesn't work, try a "cold pull": heat it, push filament in, let it cool slightly, then pull it out firmly to remove debris. Nozzles are inexpensive, so replacing a stubborn one is often quickest.
How often should I replace the FEP film on a resin printer?
Replace it when it becomes cloudy, scratched, dented or punctured, or when it no longer stays tight. How often depends on how much you print and how carefully you clean the vat.
Why have my prints suddenly started failing?
The most common causes are damp filament, a worn nozzle or build surface, loose belts, or an update that changed a setting. Work through the basics in order, starting with the first layer and dry material.
Still stuck?
Send us a photo of your print with your printer and material, and our UK team will help you work out what's going on.