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How do you determine the thread size needed to thread a steal rod and tap the female mate?

I have a steel rod measuring 7/16 (.4375 inch o.d.) I need to be able to thread into part. the die for a 7/16 thread is giving me trouble. As far as I know the rod is standard carbon steel and is soft enough to scribe and/ or grind but I can't get the the threads to start. I am new to tap and die and might be over looking something simple. I hope so and that someone can help. Thanks for any useful info.

Public Comments

1. Are you re-tapping a thread hole that something broke off inside? If so, you may need to drill and rebore to the next size up. Either way, make sure you are using oil. Keep it lubbed with 3in1 oil.
2. Try putting a slight taper on the rod this should allow a small part of the rod to be inserted into the die an make it easier to start. also be sure to use a good cutting fluid.
3. You do have the die in the die holder, I trust? The die doesn't go on real easy. The rod should be secure and the die holder with die on should be square. Apply a steady pressure and turn clockwise, Oil everything to an extreme. Slow and steady. Good luck
4. Are you going in the correct side of the die? Dies are very hard to get started. Push hard and turn until it grabs. A slight taper ground or filed on the rod end might help if you can't get the die to bite.