The grinder setting controls how coarse or fine the coffee beans are ground. A finer setting produces smaller particles, which generally slows the movement of water through the coffee and increases extraction. A coarser setting produces larger particles, allowing water to pass through more easily. The correct setting helps balance coffee strength, flavour and dispensing speed.

Coffee ground too coarsely can allow water to pass through the coffee too quickly. You may notice a fast pour, thin body, weak flavour or coffee that tastes under-extracted. If this is happening consistently, moving the grinder slightly finer may improve extraction. Make small adjustments rather than moving several settings at once.

An excessively fine grind can make it difficult for water to pass through the coffee. The drink may dispense very slowly, drip from the outlets or produce less coffee than expected. Flavour can also become overly intense or bitter. If these symptoms appear after a grinder adjustment, moving slightly coarser may help restore normal extraction.

Small changes to grind size can have a noticeable effect on extraction. Making a large adjustment makes it harder to understand which setting actually produces the best result and can potentially create new dispensing problems. Move one step at a time where possible, prepare several coffees and assess the result before making another adjustment.

There can still be coffee from the previous grinder setting inside the grinder and brewing path. It may therefore take several drinks before the new grind size is fully reflected in the cup. Avoid repeatedly changing the setting after every coffee; allow the machine a few brewing cycles before deciding whether another adjustment is required.

There isn't one universal grinder number that produces the best coffee on every machine. Grinder designs, beans, roast levels and personal taste all differ. Start from a sensible middle setting or the recommended starting position for your machine, then make small adjustments based on the result. If coffee flows too quickly and tastes weak, consider going finer; if it flows too slowly and tastes overly intense or bitter, consider going coarser.