Ukraine 11 клас Technical Drawing
Chapters: 14
1. Introduction
Role of graphic documents
- Technical Drawing: Communicating Design Ideas – Technical drawing is a shared visual language for showing the exact shape and size of an object. Designers start with freehand sketches, then use pictorial views (isometric, oblique) to show the object in 3D, and orthographic projection (front, top and side views) with standard lines, dimensions in millimetres and a scale so that anyone can make it. Today most drawings are made with CAD software.
2. Forming images on drawings
Projection methods
- Orthographic Views of Solids – An orthographic view shows a solid as seen straight on from one direction, with no perspective. The three main views are the front view (front elevation), the top view (plan) and the side view (side or end elevation). Each view loses one dimension, so we usually need all three to fix the shape. Views are arranged in a standard layout: first-angle projection (plan below the front view; used in India, Europe and ISO standards) or third-angle projection (plan above; used in the USA). Visible edges are thick continuous lines, hidden edges are dashed, and centre lines are chain lines. A net is the flat pattern that folds into a solid, and a cross-section is the shape you see when you cut through it.
3. General rules for drawings
Drawing standards
- Technical Drawing: Communicating Design Ideas – Technical drawing is a shared visual language for showing the exact shape and size of an object. Designers start with freehand sketches, then use pictorial views (isometric, oblique) to show the object in 3D, and orthographic projection (front, top and side views) with standard lines, dimensions in millimetres and a scale so that anyone can make it. Today most drawings are made with CAD software.
4. Geometric constructions
Constructions on drawings
- Geometric Constructions: Drawing Exactly with Compass and Straightedge – A geometric construction draws a figure exactly using only a compass and a straightedge (a ruler used for straight lines). Key constructions: the perpendicular bisector of a segment, the bisector of an angle, a perpendicular from a point to a line, angles of 60°, 30°, 90° and 45°, a triangle from three sides (SSS), two sides and the included angle (SAS) or two angles and a side (ASA), and regular polygons such as the hexagon. Each works because equal compass arcs make equal lengths, which give congruent triangles.
5. Constructing and reading views
Views and reading drawings
- Orthographic Views of Solids – An orthographic view shows a solid as seen straight on from one direction, with no perspective. The three main views are the front view (front elevation), the top view (plan) and the side view (side or end elevation). Each view loses one dimension, so we usually need all three to fix the shape. Views are arranged in a standard layout: first-angle projection (plan below the front view; used in India, Europe and ISO standards) or third-angle projection (plan above; used in the USA). Visible edges are thick continuous lines, hidden edges are dashed, and centre lines are chain lines. A net is the flat pattern that folds into a solid, and a cross-section is the shape you see when you cut through it.
6. Sections and cuts
Sections and cuts
- Sections of Solids – A section (cross-section) is the flat shape you get when a plane cuts a solid. Its number of sides equals the number of faces the plane passes through. A cube can give a triangle, a quadrilateral (square, rectangle), a pentagon or a hexagon. A plane parallel to a pyramid’s base gives a smaller copy of the base. In technical drawing, a section shows only the cut face; a cut (sectional view) also shows what lies behind it.
7. Representing objects
Image choice and layout
- Technical Drawing: Communicating Design Ideas – Technical drawing is a shared visual language for showing the exact shape and size of an object. Designers start with freehand sketches, then use pictorial views (isometric, oblique) to show the object in 3D, and orthographic projection (front, top and side views) with standard lines, dimensions in millimetres and a scale so that anyone can make it. Today most drawings are made with CAD software.
8. Axonometric projections; technical sketch
Axonometry
- Isometric Projection and Axonometric Drawing – An axonometric drawing shows a solid in one picture with three axes: width, depth and height. In isometric projection the three axes are 120° apart and every axis is shortened equally (scale ≈ 0.82). An isometric drawing uses full lengths instead. Dimetric shortens two axes the same, trimetric all three differently. Oblique (cavalier, cabinet) keeps the front face true size and draws depth at 45°, full length (cavalier) or half (cabinet). Circles on faces become ellipses.
9. Detail drawings: basics
Parts and working drawings
- Machine Drawing: Making and Reading Detail Drawings – A machine drawing is an exact picture of one part, made so a factory can build it without asking any questions. A detail (working) drawing shows the views of the part, section views for hidden insides, every size (dimension), how much each size may vary (tolerance), the surface finish, the material and a title block.
10. Making and reading detail drawings
Working-drawing information
- Machine Drawing: Making and Reading Detail Drawings – A machine drawing is an exact picture of one part, made so a factory can build it without asking any questions. A detail (working) drawing shows the views of the part, section views for hidden insides, every size (dimension), how much each size may vary (tolerance), the surface finish, the material and a title block.
11. Sketches of parts
Making sketches
- Technical Drawing: Communicating Design Ideas – Technical drawing is a shared visual language for showing the exact shape and size of an object. Designers start with freehand sketches, then use pictorial views (isometric, oblique) to show the object in 3D, and orthographic projection (front, top and side views) with standard lines, dimensions in millimetres and a scale so that anyone can make it. Today most drawings are made with CAD software.
12. Assembly drawings
Assembly drawings
- Assembly Drawings: How Parts Fit Together – An assembly drawing shows many parts joined together as one product. It tells you which parts there are (balloons and a parts list, also called a bill of materials), where each one goes, and how they are joined: with bolts and screws you can undo, or with rivets and welds that stay for good.
13. Joints on assembly drawings
Joints
- Assembly Drawings: How Parts Fit Together – An assembly drawing shows many parts joined together as one product. It tells you which parts there are (balloons and a parts list, also called a bill of materials), where each one goes, and how they are joined: with bolts and screws you can undo, or with rivets and welds that stay for good.
14. Reading and detailing assembly drawings
Reading assembly drawings
- Assembly Drawings: How Parts Fit Together – An assembly drawing shows many parts joined together as one product. It tells you which parts there are (balloons and a parts list, also called a bill of materials), where each one goes, and how they are joined: with bolts and screws you can undo, or with rivets and welds that stay for good.