🔍 Key Concepts

• How standard Unified/National thread callouts are written (for example: 1-8 NC LH) • Difference between diameter, threads per inch (TPI)/pitch, and thread length on a mechanical drawing • What part of the thread information is usually given separately from the basic thread designation

💭 Think About

• In a common screw-thread notation like X–Y NC, what does X usually describe and what does Y describe? • If the drawing wanted to specify the length of the threads, would that normally be built into the 1–8 NC–LH callout, or shown with a separate dimension arrow? • Is the number that tells you how many threads are in one inch normally written first or second in a callout like 1–8 NC–LH?

✅ Before You Answer

• Check standard examples of thread notes such as 1/2-13 NC or 3/4-10 UNC and see what the first number always represents. • Confirm whether thread length on this drawing is given with a linear dimension (inches along the shaft) instead of inside the 1–8 NC–LH text. • Remember that pitch (or TPI) is tied to how many threads per inch, and see which number in 1–8 NC–LH matches that role.