Abstract: A tool is provided for forming a dimple on the edge of a metal sheet to facilitate projection welding of the sheet to an adjacent metal sheet. A reversible drill motor has a housing and chuck. A mounting bracket clamps onto the housing and a base is attached to the mounting bracket. A frame is attached to the base and has spaced apart arms. A first dimple forming die is mounted on one of the arms and a second dimple forming die is slidably mounted on the other of the arms. A driveshaft has a threaded end engaged in a threaded aperture of the second dimple forming die and a drive end captured in the chuck. Rotation of the driveshaft in one direction advances the second dimple forming die toward the first dimple forming to form a dimple in a sheet edge interposed between the dies.