Abstract: This invention relates to an improved hub for diamond-edged concrete saws and, more particularly, to a hub or mandrel of the so-called "flush" type which mounts the saw blade such that the latter can make a cut while lying flush against a planar surface like, for example, a floor or wall. The hub is characterized by an rearwardly-opening donut-shaped annular groove bordering its hollow central core area which receives cooling water delivered thereto from a stationary source in the form of an inlet pipe and then disperses same centrifugally onto the remote surface of the blade mounted thereon by means of passages leading out of the groove and passing through the hub onto the aforementioned remote surface of the blade closely adjacent the central opening therein.