A spool valve has a valve body with an elongated cylindrical bore therein. Fluid passageways extend in a radial direction through the valve body and communicate with the interior bore. A peripheral port edge is defined by the intersection of the bore and the passages. A cylindrical valve spool is slidably mounted in the bore to close and open the passageways with respect to the bore. The valve spool has a cylindrical outer surface and at least one planar circular surface with a peripheral metering edge therebetween. The peripheral metering edge has a plurality of tapered notches therein which are adapted at times to overlap the peripheral port edge to permit fluid flow between the bore and the passages. The method of this invention involves creating the notches in the valve spool by positioning a knurling tool at an angle with respect to the peripheral metering edge of the spool, rotating the knurling tool with respect to the spool to permit the spaced longitudinal V-shaped projections of the knurling tool to impress in the spool the desired tapered notches.