During orthopaedic procedures, a steerable bone drill would facilitate the drilling of curved tunnel making it possible to reach difficult targets, prevent damage to surrounding tissue, or improve the fixation strength of bone anchors. This study presents the design of a flexible bone drill (Ø4 mm) that uses a hydraulic pressure wave that is transferred through a flexible, fluid-filled tube to drill through bone. The impulse is generated in the handle by a spring and is then transferred through the flexible fluid-filled tube to the hammer tip at the distal end of the drill. Seven hammer tip designs were evaluated on a bone phantom to determine the effect of tip shape on the penetration rate through bone. Although there was no clear effect of hammer tip shape on penetration rate, it was noted that blunt hammer tips accumulated dense bone material at their tip which could impede drilling performance when drilling longer tunnels. The flexible bone drill was able of effectively transmitting an impulse through the flexible tube in straight and curved orientation (45o and 90o), however, the efficiency of impulse transfer could be improved. The presented flexible bone drill design, which uses a hydraulic pressure wave to drill thorough bone, is a first step in the development of a steerable bone drill that would allow the surgeon to adjust the drilling trajectory during orthopaedic procedures.