PRINT FORENSICS / OPEN INVESTIGATION
Every failed Benchy
leaves a clue.
Don’t guess. Investigate. Turn a frustrating print into a clear, testable next step.
Open the inspection dock ↗Free · No account · Saved on your deviceTHE INSPECTION CHAMBER
Find the evidence.
Select a numbered point or a symptom below. Combine all clues you can actually observe.
Your investigation starts with one clue. Select what you see above.
A practical test sequence appears here as you collect evidence.
Keep material, model and profile fixed. Change one setting, compare under the same light, then record the result.
CASE FILE / YOUR WORKBENCH
Make the next print
a useful experiment.
Record what changed and whether the evidence improved. Your notes stay in this browser; saving is manual.
THE FIELD GUIDE
Learn to read a failed print.
01 Window threads
Fine strands across empty openings.
Retraction / moisture / heatCompare a dry spool at the same profile, then run a small retraction test. Inspect nozzle residue before changing travel settings.
02 Drooping roof
Loose strands below the cabin roof.
Cooling / bridge profileCheck the part-cooling fan and duct. Compare a short bridge test, changing only bridge speed or cooling within material limits.
03 Deck-height line
A single band at the deck transition.
Geometry / layer-time transitionCompare the line with the deck height in slicer preview. A transition band alone does not prove a loose belt or Z-axis fault.
04 Echoes on hull
Repeated echoes after sharp corners.
Motion / accelerationWith the printer cool and powered off, inspect loose fasteners and belts using the maker’s guide. Compare a lower-acceleration test.
05 Flared first layer
An outward lip around the underside.
First-layer / bed conditionsPrint a first-layer patch. Inspect nozzle gap and bed temperature against the material profile before using elephant-foot compensation.
06 Gaps in walls
Missing or thin extrusion paths.
Extrusion path / flowCheck spool drag and extruder grip. Inspect for a partial blockage using the printer guide, then verify flow with a small calibration sample.
07 Soft chimney
The small tip loses its shape.
Layer time / coolingCompare minimum layer time and fan behavior in preview. Test a longer layer time while keeping nozzle temperature unchanged.
08 Shifted cabin
A sudden sideways step across layers.
Motion / collisionStop the print. With the machine cool and off, inspect obstructions, pulley fasteners and belt routing. Recheck the machine before a slower test.
09 Vertical seam
A line of small dots at layer starts.
Seam placement / pressureCheck seam position in slicer preview. An aligned seam is expected; compare pressure advance only after flow is stable.
10 Rough bow
The steep front surface curls or sags.
Overhang / coolingInspect the underside in side light. Compare overhang speed or part cooling one at a time; separate this from wall ringing.
BEFORE YOU CHANGE A SETTING
Good questions. Better prints.
Is the Benchy hull line always a printer fault?
No. The transition from infill to deck changes layer time and cooling. Compare its height with your slicer preview before adjusting hardware. Repeated bands across the whole model deserve a different investigation.
Are the rankings a confirmed diagnosis?
No. These are transparent, symptom-based rules, not measured probabilities or photo analysis. The same symptom can have several causes. Confirm with a controlled test and your printer manufacturer’s instructions.
Why isn’t there a universal temperature or retraction value?
Material, hotend, extruder and profile all matter. Start from the manufacturer’s material profile and adjust one variable within supported limits. A value that works on one printer may fail on another.
About this lab
An independent educational troubleshooting tool for FDM makers. The boat diagrams are original illustrations, not a dimensional reference or a 3DBenchy model download. No affiliation with 3DBenchy or printer manufacturers.
Sources & reading
Prusa · Benchy hull line ↗
Prusa · Stringing and oozing ↗
Prusa · Poor bridging ↗
Prusa · Layer shifting ↗
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