A coffee grinder has a housing that includes a ring burr, a shaft extending through the ring burr, a frustoconical burr, and an interlocking plug. An internal bore of the frustoconical burr has an upper cylindrical surface adjacent the top end, an interlocking portion adjacent the bottom edge, and a tapered side surface. The interlocking plug is shaped to extend through the internal bore of the frustoconical burr, and includes an upper cylindrical portion that fits through the upper cylindrical surface, and a lower portion that includes a sidewall surface which is also tapered such that the sidewall surface interlocks with the side surface of the frustoconical burr.