The thread inserts require a special tap called an STI tap. When drilled and tapped to the size specified for the repair, the installed thread repair will yield the stated size. Here I used the milling machine after drilling to tap the hole squarely and concentric with the drilled hole. I disengaged the quill drive and used a hand wheel to turn the mill spindle. Use plenty of cutting/tapping oil always when tapping. This help prevent gouging and ripping the material you’re tapping.