It depends if you’re using a regular or a pressurized portafilter. A regular espresso machine requires a finer grind setting than a pressurized portafilter. This is because traditional machines rely on the barista to tamp the coffee, while pressurized portafilters apply that pressure on their own to create an artificial crema. A traditional espresso grind size lies in the 4-10 range, and the pressurized portafilter requires a coarser 8-12.