Over the past decades Minimally Invasive Surgery (MIS) has become a standard in abdominal surgery. Due to limited dexterity and bad ergonomics the field of MIS is shifting towards Robot-Assisted MIS (RAMIS). Simultaneously, the field is using increasingly small and steerable instruments to reduce invasiveness. Surgeon now work with fragile instruments and tissues and are not able to feel the forces they apply. This can lead to unwanted damage to patient and instrument. In an effort to reduce the risk of accidental damage, this work presents a force sensing strategy that is able to measure tip forces in RAMIS using 3mm shaft actuated tip articulated instruments. The system uses a sensorized trocar fixed to the same frame as the instrument to eliminate interfering forces occurring at the trocar. Bending in the instrument due to the applied force at the tip is measured using Hall effect sensors with a silicone transducer. Prototype testing and validation show the proposed sensing system is both accurate and reusable.