If your 3D printer is not extruding, the cause is almost always one of three things: a clogged nozzle, heat creep, or incorrect slicer settings. Work through the fixes below in order, testing extrusion after each step, and you will isolate the problem without wasting filament or time.
How to fix a 3d printer not extruding with a cold pull
The cold pull is the most reliable method to clear a blocked nozzle because it extracts the obstruction in one piece rather than pushing it deeper. Heat the nozzle to your normal printing temperature, then insert filament manually until it flows freely. Once at the target temperature, pull the filament out with steady, firm pressure. The tip of the filament should come out shaped like a slightly tapered cone, with any debris embedded in it. If the tip is flat or jagged, repeat the process. For external debris stuck to the nozzle's outside, heat the nozzle to printing temperature and carefully wipe the tip with a brass brush or use a thin 0.4mm needle to poke into the opening from the outside.
2. Check for heat creep
Heat creep happens when the hot-end fan is not cooling the heatsink properly, allowing heat to travel upward and soften the filament before it reaches the melt zone. This causes a jam that typically appears mid-print, not on the first layer. First, check that the hot-end fan is spinning continuously during the entire print; if it is intermittent or stopped, replace it. Second, remove any dust, filament dust, or debris from the heatsink fins using compressed air. Third, verify the PTFE tube (if your printer uses one) is fully seated against the nozzle inside the hotend, a gap here allows molten plastic to pool and solidify. If the fan works and the heatsink is clean, but jams persist, consider upgrading to a higher-quality fan or adding a silicone sock to the heater block to reduce radiant heat.
3. Verify your slicer settings
The most critical software setting to check is the filament diameter in your slicer, because selecting 2.85mm when your filament is actually 1.75mm will cause severe under-extrusion or no extrusion at all. Open your slicer's filament settings and confirm the diameter matches your spool; measure it with calipers in three spots to be certain. If it is below 90%, the printer is intentionally starving the nozzle. Finally, review retraction settings, if retraction distance is too high (above 6mm on a direct-drive extruder, or above 2mm on a Bowden), it can pull molten filament into the cold zone and create a plug. Reduce retraction distance by 1mm and test.
4. Adjust your nozzle temperature
If the nozzle is too cold, the filament will not melt fast enough to flow, causing the extruder motor to skip or the filament to grind. Increase the nozzle temperature in 5°C increments, printing a small test line after each change, until extrusion is smooth and consistent. Do not exceed the maximum temperature listed on the filament spool, as this can cause the filament to degrade and clog the nozzle with burnt residue. Conversely, if you see stringing or oozing, the temperature may be too high, decrease in 5°C steps until the flow is clean.
5. Inspect the extruder gear and tension
A slipping or worn extruder gear will not grip the filament, so it cannot push plastic through the nozzle even if everything else is perfect. Look at the gear teeth: if they are polished smooth, clogged with filament dust, or have visible wear, clean them with a brass brush and consider replacing the gear. Check the idler tension, on a Prusa printer, the screw head on the idler should be flush with the top of the idler arm; on an Ultimaker, the tension arm should align with the middle mark on the frame. If the tension is too loose, the filament slips; if too tight, the filament gets crushed and jams. Adjust the tension screw in small quarter-turns, then test extrusion by manually pushing filament through the hotend while the printer is idle.
6. Dry your filament to remove moisture
Wet filament absorbs atmospheric moisture, which turns to steam inside the hotend and causes inconsistent extrusion, popping sounds, and a rough, bubbly print surface. If you hear popping or hissing during printing, or the extruded plastic has a rough, matte texture, your filament is wet. Alternatively, place the spool on a baking sheet in a kitchen oven at the lowest setting (never above 80°C) with the door slightly open for 4 hours. After drying, store filament in a sealed bag with desiccant to prevent re-absorption.
7. Level the bed and set the first layer height
If extrusion stops only on the first layer, the nozzle is likely too close to the print bed, blocking the opening so no plastic can escape. Re-level the bed with a feeler gauge or a single sheet of standard printer paper: the nozzle should just grip the paper when you pull it, but not so tight that the paper tears. On most printers, this corresponds to a 0.1mm gap. After leveling, set the first layer height in your slicer to 0.2mm (or 75% of your nozzle diameter). If the nozzle was too close, you may also need to clean the nozzle tip with a needle, as the bed may have pushed debris into the opening. Test with a single-layer square print; the first layer should be smooth and uniform, with no gaps or ridges.
8. Other mechanical checks to solve extrusion problems
If you have cleared the nozzle, verified the fan, checked settings, adjusted temperature, inspected the gear, dried the filament, and leveled the bed, but extrusion is still failing, work through these less common mechanical checks. First, trace the filament path from the spool to the extruder: remove any tangles, knots, or snags, and ensure the spool rotates freely on its holder. Second, measure filament diameter with calipers at several points along a 1-meter length; if it varies by more than 0.05mm, the filament is poor quality and should be replaced. Third, for abrasive filaments like Woodfill or carbon fiber composites, use a hardened steel nozzle (minimum 0.6mm for Woodfill) because a standard brass nozzle will wear and clog within a few hours. Fourth, check the PTFE tube for kinks or pinch points, especially on Bowden setups, and replace it if the inner wall is deformed. Fifth, verify the extruder motor is getting power, if it feels cold during a print attempt and the gear does not turn, check the motor connector and the stepper driver. Finally, inspect the nozzle itself: if it is a low-quality or worn nozzle, replace it with a new one, as a deformed or oversized orifice will cause erratic extrusion.
