3D printer troubleshooting guide
Updated June 2026Independently researchedNo paid placement.
Most common FDM print failures, stringing, warping, layer separation, poor first-layer adhesion, and nozzle clogs, come down to a handful of settings: temperature, retraction, bed leveling, and print speed. Resin failures like adhesion loss or FEP sticking also have simple fixes. Change one variable at a time, use a calibration cube, and follow a symptom-to-fix decision tree to get back to reliable prints without guesswork.
Why is my print stringing or oozing?
Stringing happens when molten filament leaks out of the nozzle during travel moves. The two main culprits are retraction settings and printing temperature. If retraction distance is too low or retraction speed is too slow, the nozzle can’t pull the filament back enough to prevent drips. Try increasing retraction distance in small steps (around 0.5 mm at a time) and make sure retraction speed is at least moderate, not too fast or the filament may slip. Temperature also matters. Printing too hot reduces the filament’s viscosity, making it flow more easily and create strings. Lower your nozzle temperature by 5–10°C within the manufacturer’s recommended range. Finally, moist filament can cause excessive oozing because water turns to steam and pushes material out. Dry your filament if you hear popping or see bubbles. A simple test: print a small retraction tower to dial in both settings together.
What causes warping and how do I prevent it?
Warping occurs when the bottom layers of a print cool unevenly and contract, pulling the corners up off the bed. The biggest factor is a lack of bed adhesion combined with cool ambient air. Start by ensuring your bed is level and clean, wipe it with isopropyl alcohol before every print. Use a bed temperature appropriate for your material; for PLA that’s typically a warm bed, for ABS a much hotter one. An enclosure can help stabilize air temperature and prevent drafts, which is critical for high-warp materials like ABS and nylon. If corners still lift, try adding a brim or a raft in your slicer. These extra skirts increase the surface area gripping the bed and sacrifice a small amount of material for reliable adhesion. Also consider using an adhesive aid like glue stick or painter’s tape on glass beds. Warping is often a sign of a cold spot on the bed or a room that’s too drafty. Address the environment before tweaking hardware.
Why are my print layers separating or delaminating?
Delamination happens when layers don’t bond enough to each other, resulting in cracks or gaps between them. The most common causes are too-low nozzle temperature or too-high print speed. When the filament isn’t hot enough, it can’t fuse properly with the previous layer. Raise your nozzle temperature in 5-degree increments until you see stronger layer adhesion, but stay within the material’s recommended range. Print speed is the other lever. If you’re printing faster than the hotend can melt filament, the layers won’t have time to fuse. Slow down your print speed, especially for the outer walls and top layers. Part cooling fans can also be the problem: too much cooling on certain materials (like ABS) can prevent layers from bonding. Reduce fan speed or turn it off for the first few layers. A quick calibration cube with visible layer lines will tell you if the temperature or speed needs adjustment.
What should I do if the first layer won’t stick?
First-layer adhesion is the foundation of a good print. If it fails, the print will peel off mid-job or leave a mess. Start by checking your bed level. Use a piece of paper to set the nozzle gap at each corner, you should feel a slight drag. The bed must be clean: oils from your fingers can ruin adhesion, so wipe the surface with isopropyl alcohol between prints. For glass or PEI sheets, a thin layer of glue stick or a specialized adhesive can help. The first-layer height in your slicer matters. A typical starting point is 0.2 mm layer height with a first-layer height of 0.24–0.28 mm, which pushes filament down for better grip. Also make sure the initial layer print speed is slow, try 20–25 mm/s. If the nozzle is too far from the bed, the filament won’t squish; if it’s too close, it will scrape and clog. Adjust your Z-offset slightly if your printer has that option. A consistent, slightly flattened first line is what you’re after.
How to troubleshoot resin print failures: adhesion, layer separation, and sticking to the FEP
Resin prints have their own common issues. If the print doesn’t stick to the build plate, the usual suspects are uneven leveling, insufficient bottom-layer exposure time, or a dirty build plate. Re-level the plate with the resin vat in place, many printers now have assisted leveling. Increase bottom-layer exposure by a few seconds, and sand the build plate lightly with fine grit to improve grip. Layer separation in resin prints often means the lift speed is too fast or the exposure time for normal layers is too low. Slow down the lift speed and bump up the layer exposure by 0.5–1 second. If the print sticks to the FEP film instead of the plate, the problem could be a loose FEP, insufficient bottom exposure, or a resin that’s too cold. Tighten the FEP screws evenly, pre-warm your resin bottle in warm water (don’t microwave it), and add a few extra seconds to the bottom layers. A small calibration print like the AmeraLabs Town can help you dial in exposure without wasting resin.
How to approach troubleshooting systematically: a simple decision tree
Instead of changing everything at once, follow a symptom-based path. If the print has strings: suspect retraction or temperature. If the corners curl up: suspect warping, check bed adhesion and ambient temperature. If the layers split apart: suspect temperature or speed. If the first layer isn’t sticking: suspect leveling or cleaning. If the nozzle stops extruding: suspect a clog, check temperature and clean with a cold pull. For all symptoms, first rule out the easiest fixes: clean the bed, check that the filament is loaded properly, and confirm you’re using the right material profile. Then change one variable at a time. Use a calibration cube to test each change. If the issue crosses printer models (same problem with different filaments), it’s likely a slicer setting. If it happens only with one filament, it’s probably that spool or a clog. When a printer that worked suddenly fails, look for mechanical issues, loose belts, grub screws, or a partially clogged nozzle, before diving into slicer tweaks.
Frequently asked questions
How often should I level my bed?
Check bed level before every print that’s critical for fit or tolerance, or whenever you switch build surfaces. For casual prints, a quick paper test every few prints is fine. If you have auto bed leveling, still manually level once a month or after any major maintenance.
What is the best bed temperature for PLA?
Most PLA prints well with a bed at around 60°C. If you’re getting warping, try 65°C; if the bottom is too soft, drop to 55°C. Always check the filament manufacturer’s range, as some blends vary.
Why does my print have small blobs or zits on the surface?
Blobs are usually caused by oozing at layer starts or during travel moves. Enable “wipe” or “combing” in your slicer to hide seam points, and tune retraction settings. Also check that your filament path has no friction that causes pressure buildup.
How do I fix a clogged nozzle without replacing it?
Perform a cold pull: heat the nozzle to printing temperature, push filament through, then let it cool to around 90–100°C (for PLA) and pull it out firmly. The molten filament will often bring debris with it. Repeat once or twice. If that fails, use a nozzle cleaning needle or disassemble the hotend.
Why is my resin print sticking to the FEP film?
This usually means the bottom layers are not cured strongly enough to the build plate, or the FEP is loose. Increase bottom-layer exposure time (by 2–5 seconds), check that your build plate is level, and ensure the FEP film is tight and dent-free. Pre-warming the resin also helps.
What does a calibration cube tell me?
A 20 mm cube shows if your printer’s axes are properly calibrated. If the cube measures off by more than 0.2 mm on any side, check your steps per millimeter. It also reveals stringing, layer shifts, and elephant’s foot. Keep one cube print profile as a baseline for troubleshooting.