A modular kitchen appliance, comprising: a powerhead having a motor with an output shaft; a grinder attachment, the grinder attachment having a housing and a power coupling capable of connecting to the output shaft; a blade assembly configured to be releasably connected to the power coupling, the blade assembly having a blade for cutting, and including a transmission axle to which the blade is fixedly connected, the transmission axle configured to be releasably connected to the power coupling to transfer power to the blade; a cup for holding material to be cut, the cup being attachable to the blade assembly and having a threaded portion to allow the cup to be screwed onto a corresponding threaded portion on the housing of the grinder attachment; and wherein the blade is operational only when the cup is attached to the blade assembly; characterized in that: the blade assembly includes a blade cover at least partially enclosing the blade, the cup being attachable to the blade cover; the housing of the grinder attachment includes a ledge for retaining a plate within the housing, a spring being located between the plate and the housing for biasing the plate, the plate configured to bias the blade cover away from the power coupling in a direction in which the transmission axle is detached from the power coupling; and with the blade assembly attached to the cup, the combined cup and blade assembly are configured to be screwed onto the housing of the grinder attachment, and the appliance is configured such that as the blade cover moves upward within the housing, it pushes against the plate, which is biased by the spring, until the transmission axle engages with the power coupling. a powerhead having a motor with an output shaft; a grinder attachment, the grinder attachment having a housing and a power coupling capable of connecting to the output shaft; a blade assembly configured to be releasably connected to the power coupling, the blade assembly having a blade for cutting, and including a transmission axle to which the blade is fixedly connected, the transmission axle configured to be releasably connected to the power coupling to transfer power to the blade; a cup for holding material to be cut, the cup being attachable to the blade assembly and having a threaded portion to allow the cup to be screwed onto a corresponding threaded portion on the housing of the grinder attachment; and wherein the blade is operational only when the cup is attached to the blade assembly; the blade assembly includes a blade cover at least partially enclosing the blade, the cup being attachable to the blade cover; the housing of the grinder attachment includes a ledge for retaining a plate within the housing, a spring being located between the plate and the housing for biasing the plate, the plate configured to bias the blade cover away from the power coupling in a direction in which the transmission axle is detached from the power coupling; and with the blade assembly attached to the cup, the combined cup and blade assembly are configured to be screwed onto the housing of the grinder attachment, and the appliance is configured such that as the blade cover moves upward within the housing, it pushes against the plate, which is biased by the spring, until the transmission axle engages with the power coupling.