This is the internal rotor block of the Master Magnets bench-top dry drum separator, showing the permanent‐magnet drum (Ø ~100 mm) mounted on a spring‐supported drive hub. As the drum spins beneath a gravity‐fed feed chute, magnetic particles adhere to its surface and are carried upward before being discharged separately from nonmagnetic material. The spring‐loaded design maintains tight tolerances for consistent field strength and minimal mechanical wear. This spare rotor assembly is compatible with Model MMD-100 and ideal for refurbishing or scaling up small‐batch magnetic separation experiments on mineral powders.