Today we’re cranking infill from 10% to 90%, like my caffeine level right before a deadline. Which cubes will survive our stress test, and which ones will tap out sooner?
I’m Bryan DeLuca, and this is MakerBuildIt. We printed nine identical 1-inch PLA cubes—same printer, same filament, same everything. The only variable was infill percentage. Then we tried to poke a hole in each one with a force meter. Because science.
Test Setup (a.k.a. “No funny business”)
Constants:
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Same printer, same PLA, same nozzle, same layer height
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Infill pattern: Rectilinear (kept consistent)
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Only variable: Infill percentage (10% through 90% in 10% steps; plus a 100% reference cube we didn’t test)
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Measured print time and filament used (grams) for each cube
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Measured puncture force (Newtons) using a probe and a force meter
We locked down the variables so infill could embarrass itself fairly.
What We Saw (Quick Visual Take)
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10% infill: Big open spaces—easy for the probe to get in.
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90% infill: Looks nearly solid—only tiny marks from the probe.
As infill went up, the hole size shrank. Past ~50%, visible damage from a single probe push was minimal.
The Data (Per-Cube Metrics)
Patterns:
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+34–52 seconds per +10% step up to 50%
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+1:28–1:35 per +10% step from 60–90%
Time curve: ~linear early, then bends upward after 50%.
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About +1.67 g per +10% step on average
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From 10% → 90%, you used 3.14× the filament (+214%)
Filament curve: Almost perfectly linear the whole way.
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Time: 11:28 → 20:41 (+9:13, ~+80%)
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Filament: 6.22 g → 19.54 g (+13.32 g, ~+214%)
Totals (10% → 90%):
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Force notes: The puncture test maxed out the meter around the 50% mark (≈ 500 N). Above that, damage from a single probe push was tiny.
Context: Typical adult male grip strength is often cited around 400–500 N. This isn’t apples-to-apples with a puncture test, but it helps set a ballpark.
What It Means (And What Actually Matters)
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Infill above ~50% didn’t show dramatic additional puncture resistance in our single-probe test. You get diminishing returns in visible damage reduction.
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Walls, top, and bottom layers (aka perimeters and skins) contribute heavily to real-world part strength. Don’t sleep on them.
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Infill pattern can change failure behavior, but since our goal was apples-to-apples, we kept rectilinear for all tests.
Recommendations by Use Case
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Cosmetics & Light Duty: 10–25%
Save time and filament (and your weekend). Looks good, good enough.
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General Functional Parts: 30–50%
Reliable strength for day-to-day prints. This is the smart money zone.
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High Stiffness / Abuse: 60–80%
Use when you truly need it—but try thicker walls first, and consider a stronger geometry (ribs, fillets, chamfers).
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90%+: Usually overkill for PLA. Heavy and time-hungry with marginal gains for most parts.
Pro tip: If you’re chasing strength, start by increasing perimeters/wall count and top/bottom layers before cranking infill. Then pick a pattern that suits your load paths (gyroid, grid, cubic, etc.).
A Few Practical Notes
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Rectilinear vs Gyroid: Gyroid often spreads load more evenly and can feel “tougher,” but it also changes print time. If enough of you want it, I’ll run the gyroid rematch with the same protocol.
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Material matters: This test used PLA. PETG, ABS, and nylon will behave differently (layer adhesion, ductility, etc.).
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Strength ≠ Just Infill: Layer height, nozzle diameter, filament brand, print temperature, and cooling all affect failure modes. Keep your baseline consistent when comparing.
If your goal is strong, efficient parts, target ~40–50% infill and tune walls/skins and geometry first. Reserve 60–80% for parts that truly need the extra stiffness, and avoid 90%+ unless it’s for a specific reason (weight, machining, or you just love your printer working overtime).