Bar coffee machines: problems and solutions

In general, extraction is the process by which hot water, inside the machine, passes through the ground and blends the coffee into the cup we all know.

The entire operation oscillates with a time frame ranging from 20 to 30 seconds. During this timing of espresso coffee delivery, the over- and under-extraction, can tell us many things about our coffee. When these times are too short, i.e. under 20 seconds, the under-extracted coffee appears less full-bodied than the classic espresso; the cream tends to dissolve and the taste is too light and not very aromatic. On the contrary, when the extraction operation exceeds 30 seconds, a coffee with a rather dark colour, excessively bitter and with little aroma is produced. The cream tends to be placed on the edge and has a hole in the centre.

Therefore we list some causes and solutions that can cause over-extraction, under-extraction, and other types of problems that do not allow us to obtain a perfect coffee. Starting from questions that we often receive:

1 -> possible causes MILLER
1.1-> MILLER solution
2-> possible causes MACHINE
2.1-> MACHINE solution

Why is there no coffee delivery?

2 - The filter may be clogged due to too fine grinding
2.1 - Clean the filter well. Grind the coffee again in a larger size.

Why does the coffee come out too quickly?

1 - Grinding coffee too coarse
1.2 - Grinding the coffee again at a smaller size

Why does coffee drip down?

1 - coffee grinding too fine / over-pressing coffee
1.2 - Grind the coffee to a larger size again / Reduce pressure when pressing the coffee
2 - clogged showers
2.1 - thoroughly clean the hand showers

Why is the cream too light?

1 - coffee grinding too coarse / weak coffee pressing / low dose of coffee in the filter
1.2 - Grind the coffee to a smaller size again / Increase pressure when pressing the coffee / Check the ground coffee spout for the correct dose of coffee.
2 - water temperature lower than 90° / pump pressure higher than 9 atmospheres / clogged showers / expansion of filter holes
2.1 - increase the temperature of the water, bringing it up to full capacity / decrease the pump pressure to 9 atmospheres / thoroughly clean the hand showers / replace the filters

Why is the coffee cream too dark?

1 - Robusta coffee blend / coffee grinder too fine / high dose of coffee in the filter / excessive coffee pressing
1.2 - this may be a voluntary choice in mixing. If not to your liking, replace the blend with a higher percentage of Arabica coffee / Grind the coffee to a larger size again / Check the grinder's spout for the correct amount of coffee / Reduce pressure when pressing the coffee

Why does coffee have so little cream?

1 - low dose of coffee / weak coffee pressing
1.2 - Check the ground coffee spout for the correct dose of coffee / Increase pressure when pressing coffee

Why does the coffee cream have a poor hold and lasts for a short time?

1 - wrong grinding
2 - water temperature higher than 90°
2.1 - decrease water temperature, bringing it to full capacity

Why are splashes coming out of the spout?

1 - old ground coffee
1.2 Remove the leftover ground coffee and replace with freshly ground coffee
2 - pump pressure less than 9 atmospheres
2.1 - increase the pump pressure to 9 atmospheres

Why do the spouts deliver differently?

2 - incorrect pressure / obstruction of the nozzles
2.1 - check the pump pressure up to 9 atmospheres / thoroughly clean the nozzles

Why is coffee dripping from the filter holder?

2 - the underbody seal is leaking / there may be coffee residue on the filter holder / the filter holder may have been inserted incorrectly
2.1 - replacing the underbody gasket / thoroughly clean the filter holder / release and insert the filter holder correctly

Why are coffee grounds left in the cup?

1 - grindstones may be consumed / coffee ground too fine
1.2 . check grinders for wear and tear and replace if necessary / regrind coffee to a larger size.
2 - expansion of filter holes / lack of cleaning between filter and filter holder
2.1 - replace the filter / disassemble and thoroughly clean the filter holder