Abstract: A diamond core drill using a sealed core bit is fastened centrally by means of a hollow shaft with a slanted cut at one end, that is used in a wedging manner to secure the tool against the work surface. This eliminates the need for an exterior frame and thus permits the use of large hole saws up to 48", held by a simple and economical tool. The tool feed towards the surface is controled via an advance control nut that screws on the filleted part of the shaft. The tool has a water feed system that entraps the water in a chamber formed by the barrel of the saw and the surface to be cut, that forces the water to seep along the sawing gap thus facilitating lubrification of the core bit. The resulting configuration is such as to allow for a single tool operator.