chamfering[1]​ or chamfering[2]​ is an operation by which a chamfer is made, that is, a cut or recess on an edge "Edge (geometry)") of a solid body. Such chamfers can be made on the outer edges, for example at the ends of a shaft "Axle (mechanical)"); or on interior edges, such as hole entrances.

If a chamfer is made at the intersection of two planes, a new flat face "Face (geometry)") is obtained and two rectilinear edges less sharp than the initial one. On the other hand, if it is done at the end of a cylinder, that is, at the intersection "Intersection (geometry)") of the lateral face of the cylinder with the base, what is obtained is a conical face "Cone (geometry)") and two circular edges.

Making chamfers on pieces has various purposes, depending on the destination of the product and/or project to be carried out. For example:.

To size a chamfer in a plane, the angle of the inclined face and one of the legs is delimited. In pieces of revolution, the length of the parallel leg "Parallelism (mathematics)") is delimited to the axis of symmetry and, for the inclination, either the angle between a generatrix of the chamfer cone and the axis is delimited, or the angle between two opposite generatrices.

For 45° chamfers, a simplified notation is used in the dimension of the leg, for example "2x45º", which makes it possible to dispense with the "dimension lines" and auxiliary lines for the angle.[5]​.

To represent welded joints whose edges have been previously chamfered, symbolic representations are used or enlarged views are used to limit the detail.[6]​.