This paper presents Reach, a keyboard-based gesture recog- nition system for live piano sound modulation. Reach is a system built using the Leap Motion Orion SDK, Pure Data and a custom C++ OSC mapper1. It provides control over the sound modulation of an acoustic piano using the pi- anist's ancillary gestures. The system was developed using an iterative design pro- cess, incorporating research findings from two user studies and several case studies. The results that emerged show the potential of recognising and utilising the pianist's existing technique when designing keyboard-based DMIs, reducing the requirement to learn additional techniques.