Abstract: A threaded coupling comprising a first end, a second end, a first portion of the threaded coupling defining a first thread profile, a second portion of the threaded coupling defining a second thread profile different from the first thread profile, where at least two threads of the second thread profile proximate to the second end are reduced in height according to an extra machining angle.

Abstract: A threaded coupling comprising a first end, a second end, a first portion of the threaded coupling defining a first thread profile, a second portion of the threaded coupling defining a second thread profile different from the first thread profile, where at least two threads of the second thread profile proximate to the second end are reduced in height according to an extra machining angle.

Abstract: A threaded coupling suitable for drilling oil and gas wells is provided. The threaded coupling having a first end and a second end. A first portion of the threaded coupling proximal to the first end can have a first thread profile, and a second portion of the threaded coupling proximal to the second end can have a second thread profile that is different from the first thread profile. In particular, at least two threads of the second thread profile proximate to the second end are reduced in height according to an extra machining angle. The first thread profile and the second thread profile can further be tapered according to a taper angle.