External Sharp Corners and Intersecting Surfaces

A precisely “sharp” corner can never be produced at intersecting surfaces in metalworking. But where a sharp corner is required, it can be produced within specified limits, which usually are close enough to meet the functional requirements of the part. A dimension should be used for each intersection of surfaces where precision is required.

The intersections labeled A, B, C and D in Drawing #8 are typical to most precision machined products. These can be designated with a commercial corner break (.015″) when this will not interfere with the function of the part. However, if a “sharper” corner is required, a break not to exceed .005″ can be specified.

A note to “Break All Corners” is vague and confusing to those used to working to .001″ dimension. If a corner is critical, give it maximum and minimum dimensions. If it isn’t a critical corner, keep the tolerance as open as possible.

If a corner break is not functional, the kind of break should be left to your supplier. He may be able to use a .015″ x 45° break or a .015″ radius maximum depending on where the corner is located.