It is shown that in an oblique cutting operation two of the edge force components can be derived on the basis of the hypotheses: (a) that there exists an equivalent orthogonal cutting operation which is such that the depth of the layer of workpiece material which is extruded below the cutting edge in oblique cutting, h, is equal to that which would be extruded below the cutting edge in this equivalent orthogonal cutting operation, and (b) the area of contact between the flank face and the extruded layer in oblique cutting is that which would exist in the equivalent orthogonal cutting operation.
By applying these hypotheses, expression for the edge force component acting normal to the generated surface, Fv', and that acting along the cutting speed direction, F~', are derived and are verified using empirical cutting data. It has not proved possible to formulate a model from which the edge force component acting along the cutting edge direction, F2', can be deduced. However, on the basis of conjecture, a simple-minded argument is advanced which leads to an expression for F2'. This expression is verified using empirical force data.