Having followed up on Olderdan's hint to check the U tube videos, it would appear that the taps were made from bolts with the existing thread form. While I had always understood the basics of making a simple "thread chaser," the one video goes into detail making a real tap from an existing bolt. This is a bit more involved and requires a substantial equipment outlay. I guess I will be needing to buy the taps. Thank you for sharing all the same.