Abstract: A drill chuck and revolving spindle guard for protecting a person operating machine with a revolving spindle comprising: a mounting bracket for attachment about a machine part having a revolving spindle; a pawl adapted to fall into a slot in a block attached to the mounting bracket; a locking block through which a threaded shaft is disposed to permit pivoting for swinging the guard in and out of working position in relation to a work-piece; a threaded shaft around which a compression spring is spirally wound to permit height adjustment of the guard; a compression spring for holding the guard in a locked position; a locking nut disposed at a base of the threaded shaft around which the compression spring is wound to hold the guard fast after height or position adjustments; a guard bracket upon which a base portion of the nut rests; a guard having a semi-circular configuration; whereby the guard bracket is attached to an arc of the semi-circular guard so that when the guard is moved to a drill change position by