A good espresso usually runs at around 9 bar with an extraction time of 25-30 seconds.
Keep the dose in the basket consistent and tamp evenly. Values vary by blend and machine, so fine-tune by taste.
The four factors
- Pressure: usually around 9 bar.
- Time: usually 25-30 seconds.
- Dose: a consistent amount of coffee in the basket.
- Tamping: even pressure on the coffee.
Fixing problems
Values vary by blend and machine, so fine-tune by taste. See coffee comes out watery or bitter and adjusting the grinder.
- Watery coffee, fast flow: grind finer or add more coffee to the basket.
- Bitter coffee, slow flow: grind coarser.
- Uneven flow from the portafilter: check tamping and clean the baskets.
A small test in three steps
- Keep the dose and tamping constant.
- Time the shot from the moment the pump starts.
- If the time or taste is off, change only the grind, by one small step.
Signs that are not the grinder
- Drips or leaks around the portafilter: check the group gasket.
- Coffee suddenly runs very fast with the same setting: check the basket and pump pressure.
- Noise or vibration from the pump.
When the machine is at fault
If pump pressure is unstable or the temperature swings, the grinder cannot fix it. The machine needs service.