Speed vs Strength: How Much Do You Really Lose When Printing Fast?

The Question Every Maker Asks

You have got a Bambu Lab screaming at 500mm/s, or a Klipper-tuned Ender pushing the limits. But every time you crank up the speed, that little voice asks: Am I making my prints weaker?

A recent collaboration between My Tech Fun and Roetz 4.0 set out to answer exactly this question, and the results might surprise you.

What the Tests Showed

Researchers tested identical PLA prints at dramatically different speeds:

• Standard speed: ~60mm/s typical settings
• Extreme speed: Pushed to the printer limits

The findings align with academic research from the European Mechanical Science journal, which found that printing at 105mm/s versus 15mm/s resulted in a 12% reduction in part mass, directly correlating to reduced strength.

Why Speed Affects Strength

Three factors combine to weaken fast prints:

1. Underextrusion

At high speeds, the extruder struggles to push filament fast enough. Even with flow compensation, you get micro-gaps between layers and infill lines.

2. Poor Layer Adhesion

Faster movement means less time for each layer to bond with the one below. The plastic does not quite reach optimal temperature before the nozzle moves on.

3. Reduced Infill Density

Studies showed part mass decreased as speed increased, indicating the printer was not laying down as much material per layer, even with 100% infill settings.

The Real-World Numbers

Here is the brutal truth from the research:

That is an 87% time saving for a 12% strength penalty. Whether that trade is worth it depends entirely on your use case.

When Speed Makes Sense

Go fast when:

• Visual prototypes - Does not need to survive a fall
• Iterative design - You need 20 versions today
• Non-structural parts - Enclosure panels, cable guides, decorative items
• Draft mode - Preview prints before committing to quality settings

When to Slow Down

Take your time when:

• Functional parts - Brackets, mounts, load-bearing components
• Threads and fits - Screws and mating surfaces need precision
• Outdoor use - UV exposure amplifies weak layer bonds
• Thin walls - High speed exaggerates wall defects

Practical Settings to Preserve Strength

If you want speed without sacrificing too much quality:

• Keep outer walls slow: 40-60mm/s for visible surfaces
• Speed up infill: Infill can run 2-3x wall speed
• Increase temperature slightly: +5-10°C helps flow at speed
• Use a larger nozzle: 0.6mm or 0.8mm flows better fast
• Consider PETG: Better layer bonding at speed than PLA

The Verdict

Speed costs strength - but not as much as you might fear. A 12% reduction for an 87% time saving is a reasonable trade for most non-critical parts.

The real insight is this: print speed is a tool. Use it intentionally. Fast for prototypes and visual checks. Slow for final parts that need to survive the real world.

Your printer can probably go much faster than you think. Just know what you are trading when you push that slider up.