Abstract: Improved guard and blade assemblies for a rotary cutting machine; wherein the guard has a full rear skirt, and an apertured front skirt of three designs of guard element mounted in cantilever; and wherein the cutter blade is of the swivel type but with retention means for the cutter blade designed to warn the operator of swivel blade pivot failure and with the blade being replaceable without need to disassemble the cutter head; the cutter blade has apertures for adjustable weighting of the swivel blade to provide a variable moment arm; an improved design of replaceable blade tip is also proposed for propeller-type and swivel-type blades.