Lesson Notes By Weeks and Term v5 - Grade 11
Mechanical drawing: fasteners and machine components – Week 3 focus
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Mechanical drawing: fasteners and machine components – Week 3 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Engineering Graphics and Design
Class: Grade 11
Term: 2nd Term
Week: 3
Theme: General lesson support
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This week, we delve into the fascinating world of fasteners and machine components. These are the building blocks of almost everything around us, from cars and bicycles to the bridges and buildings that shape our cities. Understanding how these components are designed and represented in technical drawings is crucial for any aspiring engineer, technician, or designer. This is especially important in South Africa, where infrastructure development and manufacturing are key sectors driving economic growth. By mastering these skills, you'll be equipped to contribute to the design, construction, and maintenance of the essential infrastructure that keeps our country moving.
2. 1.
Fasteners: An Introduction Fasteners are mechanical devices used to join two or more parts together. They can be temporary (e.g., bolts and nuts) or permanent (e.g., rivets and welds). This week, we'll focus on temporary fasteners that are commonly used in mechanical assemblies. 2.
2. Bolts and Nuts A bolt is a threaded fastener that is used with a nut to clamp materials together. A nut is a fastener with a threaded hole that is used to tighten onto a bolt.
Common bolt and nut combinations include: Hexagon Head Bolt and Nut: The most common type. They are relatively easy to tighten and provide good clamping force.
Square Head Bolt and Nut: Less common now but still found in older machinery.
Drawing Conventions: Across Flats (AF): The distance between parallel flat sides of a hexagon or square head. This is a critical dimension for selecting the correct wrench size. In general, AF is approximately 1.5 bolt diameter (D)* Thickness (T): The height of the nut or head of the bolt. T is usually 0.8 D Bolt Length (L): Measured from the underside of the bolt head to the tip of the bolt.
Thread Length: Typically 2 D + 6mm.