Craniotomy and Brain Tumor Biopsy are sorts of neurosurgeries related to the brain. A craniotomy is a bone flap removal from the skull surface which is an essential procedure in open skull surgeries. A craniotomy can be a time-consuming process, and the large forces needed for the cutting process make surgeons exhausted before operating the critical brain tissue. As a result, the probability of further errors increases. On the other hand, Brain Tumor Biopsy is a high accuracy surgery that involves a needle insertion to the tumor through a specific pre-planned trajectory. Surgeons still use a stereotactic frame as needle guidance. This frame is a half-century technology that can involve human errors during measurement and mounting processes. Nowadays, High stiffness robotic systems can achieve precise positioning and guidance without frames, save time and effort, and enhance safety. This paper presents a new