Illinois, Indiana, Michigan, Wisconsin, Iowa or anywhere, the answer to your cutting tool problems is here at General Cutting Tools in Chicago. Our master tool makers have decades of experience making tooling work for difficult operations; grinding the correct profile and relief. In sharpening twist drills the tool lands containing the two cutting edges are ground. Each flank consists of a curved surface which provides the relief needed for the easy penetration and free cutting of the tool edges. In grinding the flanks, the drill is swung around the axis of an imaginary cone while resting in a support which holds the drill at one half te point angle with respect to the face of the grinding wheel. Feed for stock removal is in the twist drill and is also specified by that value. It is not a constant but should increase toward the center of the drill.
The relief grinding of the flank surfaces will generate the chisel angle on the web of the twist drill. The vale of that angle, typically 55 degrees, which can be measured, for example, with the protractor of an optical projector, is indicative of the correctness of the relief grinding.