A good expresso will depend on the right grinding of the coffee bean. A good espresso takes around 30 seconds to extract and be about 30ml. Any extractions faster than this will result in not enough flavour being extracted, and the drinks will be weak. When the grind is too coarse, the grounds will not pack tightly together, and the water will pass through them too quickly. The extraction will be too fast, and the drinks will be weak. You must make the grind finer.