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3D Print Troubleshooting, Calibration & Parts

Symptom diagnoser

What went wrong with your print?

Pick the symptom you can see on the plate. Every fix here is written against a specific failure mode, with the settings that actually change it.

3D print troubleshooting by symptom: a part that never stuck is an adhesion fault, gaps and thin lines are extrusion, and an offset part-way up is motion. 3D Print Troubleshooting: Find the Fault by What You Can See What to look for Three cheap things diagnose most of what follows. A tool kit with nozzle needles, tweezers and hex keys… Diagram of a layer stack showing the seam print defect. Blobs, zits and a visible seam line A small defect where each layer starts and stops, stacked into a visible line. Diagram of a layer stack showing the crack print defect. Cracking and layer delamination Layers separate under load or on their own. Weak bonding from cold plastic or a cold chamber. Diagram showing overhang angle measured from vertical, with the 45 degree rule of thumb and a drooping unsupported edge. Drooping overhangs and failed bridges Plastic sags before it sets. Cooling and slower perimeters do most of the work. Diagram of a layer stack showing the foot print defect. Elephant foot on the bottom layer The first layers bulge outwards. Too much squish plus a bed hotter than it needs to be. Build plate pairings for first layer adhesion: PLA on PEI with no glue, PETG on textured PEI or smooth PEI with glue, ABS and ASA on smooth PEI with glue and a closed enclosure, TPU on textured PEI at low bed temperature. First Layer Not Sticking: What 3D Printer Bed Adhesion Depends On Nine times out of ten the plate is contaminated with skin oil, not badly levelled. Wash it before you touch the Z offset. Diagram of a layer stack showing the shift print defect. Layer shifting partway through a print Everything above a certain height is offset. Belts, grub screws or a speed the machine cannot hold. Diagram of a partially clogged nozzle showing debris restricting the melt zone above the nozzle orifice. Nozzle clogged: partial and complete blockages A partial clog degrades quality gradually; a complete one stops everything. The cold pull handles both. Diagram of a layer stack showing the detach print defect. Print detached mid-print and turned into spaghetti The part came off the plate and the nozzle kept extruding into air. Adhesion, warping or a knock. Diagram of a layer stack showing the ring print defect. Ringing and ghosting on vertical surfaces Echoes of a corner repeating across the wall. Mechanical vibration the frame cannot damp fast enough. Drying temperatures to cure stringing: PLA 4 hours at 55 C, PETG 4 hours at 65 C, ABS and ASA 4 hours at 80 C, TPU 6 hours at 55 C. Stringing and oozing between parts Fine hairs across gaps. Moisture first, temperature second, retraction third — in that order. Diagram of support structures under a part showing the interface gap between the support top and the part underside. Supports that will not come off Supports fused to the part. Increase the Z gap and reduce the interface density. Diagram of a layer stack showing the gap print defect. Under-extrusion: thin, gappy walls Not enough plastic is arriving. Partial clog, worn nozzle or an uncalibrated flow rate — check in that order. Warping risk by material: PLA very low shrinkage with no enclosure needed, PETG low with an enclosure helpful for large parts, ABS and ASA high shrinkage with an enclosure required. Warping: corners lifting off the bed Plastic shrinks as it cools and pulls the corners up. Heat is the fix, not adhesion tricks. Diagram of a layer stack showing the band print defect. Z banding: repeating horizontal lines up the print Bands at a regular pitch. Measure the spacing — it tells you which part is at fault.
Not a print defect? Error codes  ·  Calibration  ·  Filament
T1 Print defects Stringing, warping, first layer, under-extrusion 15 articles T2 Error codes HMS, MINTEMP, thermal runaway, homing failed 28 articles T3 Calibration Z offset, flow, pressure advance, input shaper 9 articles T4 Filament Temps, drying, enclosures, PLA vs PETG vs ASA 55 articles T5 Parts & fit Nozzles, plates, hotends — and what fits what 84 articles T6 Slicer OrcaSlicer, Bambu Studio, Cura, PrusaSlicer 10 articles T7 Upgrade & buy Which printer, which AMS, what fits your filaments 216 articles
HMS, MINTEMP, thermal runaway, homing failed

Error codes

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HMS 0300-9300-0001-0006: chamber temperature sensor fault The chamber temperature reading has become implausible. It affects heated chamber control, not the hotend or the bed. HMS 0300-0100-0001-0008: heatbed heats too slowly The bed is heating, but not at the rate the printer expects. Usually ambient conditions or a draught rather than a failed heater. HMS 0300-1000-0002-0001: X axis resonance frequency low The measured resonance of the X axis has dropped below the expected band. Nearly always belt tension. HMS 0300-0600-0001-0001: motor A open circuit One of the two CoreXY motors reads as disconnected. On a CoreXY machine, losing one motor breaks both axes at once. HMS 0300-1d00-0001-0001: extruder position sensor fault The feedback that tells the printer the extruder is actually moving filament has stopped making sense. HMS 0300-0900-0001-0002: extruder motor short circuit The extruder motor is drawing more current than its winding resistance allows. Unlike the open-circuit code, this one usually is the motor. HMS 0300-0900-0001-0001: extruder motor open circuit The extruder motor reads as disconnected. Usually the toolhead connector rather than the motor windings. HMS 0300-0900-0002-0002: extrusion resistance too high The extruder is meeting more resistance than expected. Either the melt path is restricted or the filament is not moving freely into it. HMS 0300-0300-0001-0001: hotend cooling fan stopped The hotend cooling fan is turning too slowly or not at all. This is the fan that stops the filament softening above the melt zone. HMS 0300-0200-0001-0007: hotend temperature sensor fault The hotend thermistor is reading implausibly. The sensor tells the printer how hot the nozzle is, so the machine stops rather than guess. HMS 0300-0200-0001-0002: hotend heater open circuit The hotend heater reads as disconnected. Usually a pulled crimp at the connector, sometimes a broken lead, occasionally the cartridge itself. HMS 0300-0200-0001-0001: hotend heater short circuit The hotend heater cartridge is drawing more current than its resistance allows. A short in the cartridge or its lead.
Z offset, flow, pressure advance, input shaper

Calibration

All calibration →
01 Temperature tower for 3D printing: use 5 degree steps, judge bands on bridging and stringing rather than surface gloss. Temperature Tower: How to Run One and What to Read From It 4 min read 02 3D printer test prints in order: first layer and flow first, then temperature and retraction, with speed and acceleration last. 3D Printer Test Prints: Which Ones Actually Tell You Something 4 min read 03 3D printer bed temperature: PLA runs 55 to 60 degrees and PETG 75 to 85, with the plate surface typically 5 to 15 degrees below the reported number. 3D Printer Bed Temperature: Settings by Material, and Why Yours Reads Wrong 4 min read 04 Order to calibrate a 3D printer: bed levelling then Z offset, extruder steps then flow rate, and finally motion tuning with pressure advance. How to Calibrate a 3D Printer: The Order That Stops You Going in Circles 2 min read 05 Calibration cube for 3D printers: a 20 mm cube, normal FDM deviation within 0.1 mm, and a caliper reading to 0.01 mm needed to measure it. The Calibration Cube: What It Actually Measures, and in What Order 2 min read 06 Key figures for Bed levelling and mesh compensation: 121 points on 420 mm, 16 points on 180 mm. Bed levelling and mesh compensation 2 min read
Temps, drying, enclosures, PLA vs PETG vs ASA

Filament

All filament →
Nozzles, plates, hotends — and what fits what

Parts & fit

All parts & fit →
01 3D printer lubricant: synthetic grease on lead screws, a thin film on rails and rods, and nothing at all on belts, extruder gears or the build plate. 3D Printer Lubricant: What Goes on Rails, Screws and Nothing Else 4 min read 02 Heat set inserts for 3D printing: an insert that spins means the hole is too large, a split boss means too small, and one sitting proud means the iron is too cool. Heat Set Inserts for 3D Printing: Hole Size, Iron Temperature and Seating 4 min read 03 Sanding and priming 3D prints: knock down layer lines at 180 to 220 grit, level at 320 to 400 before primer, then cut the primer back at 600. Sanding and Priming 3D Prints: The Grit Order That Actually Works 4 min read 04 Cleaning a 3D printer bed: isopropyl alcohol handles oil, hot water and dish soap remove the polymer film, and acetone must never touch PEI. Cleaning a 3D Printer Bed: What Works on PEI, Glass and Textured Plates 4 min read 05 3D printer stepper motors: NEMA 17 describes the 42 mm mounting face, holding torque runs 40 to 60 Ncm, and each coil should read between 1 and 5 ohm. 3D Printer Stepper Motors: Sizes, Torque, and When One Has Actually Failed 5 min read 06 Bambu Lab nozzles come as proprietary hotend assemblies rather than MK8 or V6 threaded tips, split between the P1 and X1 generation and the P2S and H2 generation, and moving from 0.4 to 0.6 mm roughly doubles flow. Bambu Lab Nozzles: Why You Replace the Hotend, Not Just the Tip 2 min read
OrcaSlicer, Bambu Studio, Cura, PrusaSlicer

Slicer

All slicer →
01 3D printer retraction settings: direct drive needs 0.5 to 2 mm, Bowden needs 4 to 7 mm, and retraction speed sits between 25 and 45 mm per second. 3D Printer Retraction Settings: Distance, Speed, and What They Cannot Fix 5 min read 02 3D printer layer height: the ceiling is 75 to 80 percent of nozzle diameter, about 0.3 mm with a 0.4 mm nozzle, and halving layer height roughly doubles print time. 3D Printer Layer Height: The Nozzle Sets the Ceiling 2 min read 03 Key figures for Importing Cura profiles into OrcaSlicer: 0.4 mm nozzle, 0.2 mm layer, 0.42 mm width. Importing Cura profiles into OrcaSlicer 2 min read 04 Key figures for Max volumetric speed: the real limit on print speed: 40 mm³/s hotend, 0.2 mm layer, ~380 mm/s ceiling. Max volumetric speed: the real limit on print speed 2 min read 05 Infill pattern comparison: gyroid is isotropic with no self-crossing, grid is fast and strong in two axes, cubic is good all round, lightning uses minimal material. Infill patterns: gyroid, grid and when it matters 2 min read 06 Diagram comparing a brim, a flat ring of extra outline around the first layer, with a raft, a printed slab underneath the whole part. Brim vs raft: which one and when 2 min read
Which printer, which AMS, what fits your filaments

Upgrade & buy

All upgrade & buy →