A rotary cutting tool for forming fluted rotors and the like comprising a cylindrical body having a plurality of metallic carbide cutting blades which are detachably mounted on the circumference of the body. The blades are arranged along a helical line with respect to the axis of rotation of the cutter body. The blades may be circumferentially spaced apart equidistant, one blade from each adjacent blade, to form only one turn of the helix and whereby each blade may be easily ground to a precise cutting edge contour while mounted on the cutter body. The cutting edge contour of each blade may be such that each blade cuts portions along the entire profile of the form produced on the workpiece.