Internal keyway

Such a difficult feature is the internal keyway.  Even if we use the appropriate manufacturing process, the end of the internal keyway wouldn't be as we designed it. Due to the cutting tool and the dimensions of the key we must make the keyway larger in order to have a correct key assembly. But making keyway larger we increase process time and we have a less "nice designed" part. Providing a drilled hole is a correct way to terminate an internal keyway.