Review on 🌺 Revitalizing Threads: Introducing the Brand Spring Center Knurl Threading by Jorge Maertz

Half-inch shaft fits into the appropriate collet on a milling machine, or you can simply slide it into a Jacobs chuck (on a milling, turning or drilling machine) if required. You don't need absolute precision for most threads, just center it on the hole to within a few thousand and you're good to go I think - once it's level it becomes really easy to cut a nice straight hole. I use mine for pretty much everything I need for internal threading.