The present disclosure includes an extraction assembly for use in an automatic espresso brewer. The extraction assembly includes components and methods for controllably extracting espresso beverage from a quantity of brewing substance. The components, assemblies, and methods facilitate improved control and operation of the extraction assembly and improve the reliability of the extraction assembly. The brewing substance is compacted between a pair of opposing pistons. Compacting force is monitored through at least one sensor carried on the extraction assembly to provide a signal to a controller. A predetermined compacting force may be programmed into the system for all brewing cycles or dependent upon the brewing substance used. The pair of pistons operates relative to a brew chamber for use in the espresso extraction process. The pistons provide compacting force and boundaries within the chamber and facilitate removal of a spent brewing substance puck at the end of the brewing cycle. Compacting force is monitored at the start of the brewing process and a predetermined force is required before the brewing process can be started. During the brewing process compacting force can be maintained and controllably adjusted. A variety of sensor methods and locations can be used to detect and monitoring compacting force.