A method and apparatus to affix a tool downhole in a cased wellbore, one embodiment comprising a tubular body with a slot along its length. A portion of the slot is V-shaped to accommodate a wedge with a corresponding V-shape. The outside of the tubular body has integral teeth. To set the apparatus, the wedge is driven into the V-shaped slot. This movement widens the slot and expands the diameter of the tubular body until it intersects with the casing. The teeth on the outside of the body bite into the casing wall to affix the tool to the casing.