Siji Coffee Grinder

The Ligre Siji grinds to a tenth of a gram, and a long-term test run with KUKA robot technology confirmed that precision was still holding on the 50.000th repetition.

Grinding by weight starts with scales built into the grinder. They zero themselves when the portafilter is hung in, then weigh the coffee as it lands. The difficulty is that ground coffee is still falling through the air between chute and portafilter when the target is reached, so a grinder that simply stops at the number will overshoot. The Siji uses predictive software that accounts for that airborne coffee and stops the motor early enough for the 0,1 gram figure to hold. With touchless grind, the process starts by itself about a second after the portafilter goes in and ends when the set amount is reached.

The burrs are flat, stepless hard steel discs, each 55 mm across. A grind by time mode is there for larger quantities. The portafilter angle is set with a patented eccentric mechanism on the rear wall, and after transport the scale can be recalibrated with a standard weight or, failing that, some coins.

The grind-by-weight invention came from the R&D team of Gronbach, a German family business, and the Siji won the iF Design Award 2024. The odd detail is the coins: a machine this exact is happy to be checked against loose change.