I have an 1984 Jet-16 Mill Drill that I am converting back to manual. The machine never came with handles to raise and lower the quill. I can't tell what the thread pitch of the handles was based on the threaded holes. I'm guessing the handles were 1/2" or 12mm. None of my thread pitch gauges seem like a great fit. I can only get a 1/2-13 and a 12x1.75mm bolt to go into the hole about three threads. I'm hoping to chase the threads and make new handles. Would someone mind measuring the thread pitch for me. I'd really appreciate it.