1. Define fit, allowance, tolerance, and limits. 2. How are external UNC threads classified? 3. Name and describe three classifications of UNC fits. 4. How are thread fits designated for the ISO...

1. Define fit, allowance, tolerance, and limits.

2. How are external UNC threads classified?

3. Name and describe three classifications of UNC fits.

4. How are thread fits designated for the ISO threads?

5. Why was the ISO metric system of threads adopted?

6. Describe a thread designated as M 56 5.5.

7. Name five thread forms used in North America and state the included angle of each.

8. What are the principal differences between the American and Unified threads?