Abstract: A cutting machine having a circular cutting tool, such as a saw blade for cutting a workpiece in two, has the blade mounted on an arm to swing from an inactive or raised position above the workpiece down into engagement with the latter. A guard protects the operator of the machine from the blade and includes a cylindrical cover journaled to turn relative to the blade and enclosing both sides and the edge of the blade. A notch is formed in the cover and faces away from the operator when the blade is in the raised position and a link turns the cover automatically as the blade is lowered so that the notch faces downwardly and exposes the blade to the workpiece. When the blade is in the raised position, the notched portion of the cover projects into a shell so that the blade is completely enclosed at that time.