A coffee grinder assembly for a coffee machine comprises two coaxially
arranged grinding wheels. One of the grinding wheels is driven by an
electric motor, and the other one is stationary. For receiving the
grinding wheels, two grinding wheel support members are provided. Each
grinding wheel is provided with radially extending protrusions, and each
grinding wheel support member is provided with corresponding recesses to
form a bayonet closure. By such a design, the provision of connecting
bores in the grinding wheels can be avoided, resulting in an enlarged
effective grinding surface.