A guide attachment for a rotary hand tool is disclosed that comprises a housing, an adapter and a removable base. The attachment is configured to remove grout from between adjacent tiles, such as floor or wall tiles. The housing of the preferred embodiment is configured to permit a tool bit to engage a work surface at the normal intersection of two planes. The removable base of the preferred embodiment permits the attachment to work on flat surfaces. The base is also reversible and contains multiple sets of guide points for guiding the tool bit along grooves that have different widths. The preferred embodiment can also include a vacuum adapter that is attachable to the housing and allows a vacuum hose to be coupled to the guide attachment for removing debris during operation. The configuration of the housing or locking mechanism accommodates adapters having different circumferences.