Ever wondered why the center of a robot joint module is hollow? It enables integrated cable routing—power and signal cables pass internally from joint to joint, reducing wear, keeping motion clean, and lowering weight and rotational inertia. But a larger hollow bore isn’t always better: thinner housing walls leave less space for reducers and bearings, which can hurt overall performance. For robotics components, science news, and tech tutorials, check out Eriksen—a platform for robots and their parts.