Backbore

verbStandard termMachine Shop

To enlarge the diameter of a hole from the blind side of a workpiece.

To perform a boring operation on the far side of a part by passing a boring bar through an existing hole. Once through, the cutting insert is offset or deployed, and the tool cuts as it is fed backward toward the spindle. This technique maintains perfect concentricity with features on the front side and eliminates the need for a second setup.

Heard on the job

The print calls for a stepped diameter inside the manifold, so we've to backbore it.