Joining Methods & Thread Calculations is one of 9 topics in the Grade 12 Mechanical Technology CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. What is the crest diameter of a screw thread also known as?
The major or nominal diameter
The root or minor diameter
The effective diameter only
The lead
Answer: The major or nominal diameter — The crest diameter is also called the major or nominal diameter, the largest diameter measured across the outermost points (crests) of the thread, used to name the thread size.
Easy
2. Which diameter is measured at the bottom (root) of the thread groove and is relevant to tapping drill size?
The root (minor) diameter
The crest (major) diameter
The effective (pitch) diameter
The lead
Answer: The root (minor) diameter — The root diameter (minor diameter) is measured at the bottom of the thread groove and is the diameter relevant to calculating the correct tapping drill size.
Medium
3. Name the diameter that a screw thread micrometre measures directly, lying between the crest and root diameters where thread and groove widths are equal.
Answer: effective diameter — The effective (pitch) diameter lies between crest and root diameters and is the diameter a screw thread micrometre measures directly.
