Abstract: The invention relates to a rotary tool having at least one replaceable cutting blade, the or each received in a channel and clamped firmly therein. The tool body has a passage in each channel which receives a safety member in the form of a pin projecting into a recess in the blade. In normal use the pin remains out of contact with the walls of the blade recess, engaging with the recess only if the clamping means fail, so as to restrain the blade from falling out of the channel.

Abstract: The invention discloses a rotary tool, for example a milling cutter, having a tool body 2 including at least one helical seating channel into which is brazed, bonded or clamped a cutting blade (8, 18, 30). The blade(s) is/are helical strips of high speed steel or tungsten carbide having a leading edge to cut a work piece. A leading face (10) of the blade has wave-form or castellated grooves to give an undulating or serrated leading edge so that the metal removed from the work piece is removed in small clips not in long lengths of swarf. In examples given, the grooves of the leading face are provided with stop ends (26) to act as a brazing or bonding key. An outer surface (36) of the blade may also be undulating, if required.