HiBREW H10A Brewing Guide & G3A Grinder Calibration Reference

For first-time users of a home semi-automatic espresso machine and grinder, understanding grind size adjustment is one of the most crucial steps in shaping coffee flavor. Bean origin, roast profile, blend composition, and brewing temperature all directly influence the quality of the cup.

Purpose:
This article aims to provide a scientifically calibrated reference (for guidance only) to demonstrate how grind size affects extraction. Based on measured data, we offer practical grind recommendations for different brewing methods to help users quickly get started and fine-tune their coffee flavor.

I. Core Principle: How Does Grind Size Affect Coffee?

Grinding is one of the most important variables in brewing. It directly determines the surface area of coffee in contact with water, which in turn controls extraction speed and flavor release.

1. Grind Too Fine

• Problem: Very small particles → large surface area → high resistance to water flow → over-extraction.
• Flavor outcome: Harsh bitterness, astringency, muddiness; may clog espresso machines (slow drips, blockages); in pour-over, water pools and extraction drags on.

2. Grind Too Coarse

• Problem: Large particles → small surface area → water flows too quickly → under-extraction.
• Flavor outcome: Sharp acidity, thin body, weak flavor, low sweetness; in espresso, fast flow with pale crema; in pour-over, short extraction time and sour taste.

3. Grind Just Right

• Goal: Balance extraction within the ideal time window, releasing acidity and sweetness while avoiding excessive bitterness.
• Flavor outcome: Smooth mouthfeel, balanced acidity and sweetness, clear layers of flavor, showcasing bean origin.

II. Calibration Standard: Establishing a Reference Point

To establish an objective calibration, we used the industry-standard #20 sieve (0.85 mm aperture) for cupping tests.

• Method: Set grinder to 13 clicks, grind 10g coffee, sift through #20 sieve for 1 minute.
• Result: 7–7.5g passed through (70–75%).
• Conclusion: This aligns with the SCA (Specialty Coffee Association) cupping standard. Therefore, 13 clicks on the G3A grinder is the “cupping calibration point”, serving as the baseline for all subsequent recommendations.

III. Recommended Grind Ranges by Brewing Method

Based on the cupping calibration (13 clicks), here are practical ranges:

1. Pour-Over Coffee | Recommended: 13–21 clicks

• Grind range: Medium-fine to medium-coarse.
• Flavor impact:
  • 13–15 (medium-fine): Closer to cupping standard. Higher extraction efficiency, fuller body, more concentrated flavor. Ideal for light roasts or faster drippers.
  • 16–18 (medium): Versatile starting point. Balanced extraction, acidity, and sweetness. High tolerance.
  • 19–21 (medium-coarse): Lower extraction, cleaner mouthfeel, tea-like clarity. Suited for dark roasts (to avoid bitterness), Chemex, or bright-fruit brews.
• Tips:
  • Beginners should start at 17 clicks.
  • If sour/thin → grind finer.
  • If bitter/astringent → grind coarser.

2. Espresso | Recommended: 6–8 clicks

• Grind range: Extra fine.
• Flavor impact: Espresso requires high resistance for 9 Bar extraction.
  • 6 clicks: Very fine, slow flow, high extraction → intense, bold, risk of bitterness.
  • 8 clicks: Slightly coarser, faster flow, lighter body → risk of sourness.
• Tips:
  • Start at 7 clicks. With 18g dose, aim for 36g output in 25–30 seconds (1:2 ratio).
  • If <25s (too fast, sour) → grind finer.
  • If >30s (too slow, bitter) → grind coarser.

IV. Conclusion & Key Reminders

1. Reliable baseline: 13 clicks = SCA cupping calibration point.
2. Clear ranges: 13–21 for pour-over, 6–8 for espresso.
3. Bean differences: Dark roasts usually require coarser settings, light roasts finer.
4. Taste is the ultimate guide:

• • Bitter/astringent → coarser.
  • Sour/thin → finer.
  • Balanced flavor → you’ve found the sweet spot.