A simple logic, if the coffee flows slowly and the water does not go out, it means there is a gap in the coffee powder between the beans. It's too dense, and if they are all crowded together, of course things won't be able to get down.

On the contrary, if the flow rate is too fast, it means that the gap is too large and everyone will stand far away. Of course, it all went down with a splash.

So the conclusion is drawn. If the flow rate is too fast, grind the coffee powder finer. If the flow rate is too slow, grind the coffee powder coarser.

Depending on the different grinders, one bar will take about 2 to 3 seconds. There will be a slight deviation depending on the different grinders.

This method is universal. If you want to control the flow rate by adjusting the thickness of the coffee powder, use this logic.

Another little tip for hand brewing: for beans that are relatively medium-dark roasted, the grinding degree will be relatively coarse.

In hand-brewed coffee, there are more light roasted beans (coffee beans with more obvious floral and fruity flavors), so you can use a relatively finer grinding degree.

Specific steps:

1. Determine the direction of adjustment you need (fine or coarse). Make sure there are enough coffee beans in the bean bin and that the valve between the bean bin and the grinder is open so that the coffee beans can fall into the grinding area smoothly.

2. Turn on the grinder for 10 seconds and clean out the coffee grounds remaining in the grinder (these are coffee powder that has not been adjusted to the grinding degree or remains from the previous scale). 

3. Use the adjusted grinding thickness to grind the coffee and make a cup of coffee, while ensuring that the powder amount, smoothing and pressing steps are accurate.

The standard for making espresso is: 20-30 seconds extraction time, and the powder to water ratio is about 1:2. For example, 18 grams of coffee powder produces 36 grams of coffee liquid.