A method of reinforcing threads. Firstly, provide a workpiece. Secondly, determine the position on the workpiece that a hole is to be drilled and into which threads are to be tapped. Thirdly, bore an opening in the workpiece which transversely intersects the hole. The opening must have a diameter which is greater that a diameter of the hole. Fourthly, insert an insert into the opening in interference fit relation. The insert is of a harder material than the workpiece. Fifthly, bore the hole through the workpiece and into the insert. Sixthly, tap threads in the hole, such that a portion of the threads are reinforced by virtue of being tapped into the harder material of the insert.