Abstract: The present invention relates generally to a spade drill blade and more particularly to a spade drill blade which is adapted to be clamped in the clamp slit of a holder and which has side surfaces that bear against the wall of the bore to be of a raised shape in such a way that during drilling it bears in extremely narrow lateral surface region in a diagonal plane against the inner surface of the bore, and the improvement, therefore, relates to the configuration of the blade with a very narrow contact area between the lateral surfaces of the cutting blade and the wall of the workpiece bore which reduces high surface friction and the risk of jamming or seizure and premature wear which prevents indexing to present the second cutting edge of the blade in the workpiece bore. The raised portion may be shaped in cross section, for example, as a ridge, trapezium, beading, lips or of other forms.

Abstract: A cylindrical deburring tool is provided with a diametric guide slot extending through the body with a pair of cutter blades received in said guide slot for radial displacement therein and spring-biased apart to a position determined by an adjustable abutment means acting on each blade.