1. Basic Drafting Skills - Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Drafting – Product Design & Architecture
Basic Drafting Skills - Line Conventions
Project Lead The Way, Inc.
Copyright 2007

2. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Lines of varying style and thickness are used in specific ways to develop and communicate graphic messages about an object’s geometry. The next few slides show some basic line conventions and their use.
Project Lead The Way, Inc.
Copyright 2007

3. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Construction Line
Construction Line: Very lightly drawn lines used as guides to help draw all other lines and shapes properly.
Ask students after slide first appears: What do you notice about this sketch? (Making sure you lead them into looking at the different line conventions or types that appear in the sketch). Imagine if all the lines here had the same thickness, weight and consistency. What do you think this sketch would look like then?
Project Lead The Way, Inc.
Copyright 2007

4. Line Conventions Object Lines: Lines are thick
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Object Line
Object Lines: Lines are thick
and dark; used to define the
object.
Object Line
Project Lead The Way, Inc.
Copyright 2007

5. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Hidden Line
Hidden Line: Lines used to show interior detail that is not visible from the outside of the part.
Hidden Line
Project Lead The Way, Inc.
Copyright 2007

6. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Center Line
Center Line: Lines that define the center of arcs, circles, or Symmetrical parts. They are half as thick as an object line.
STOP PRESENTATION: Students have the line conventions needed for the activities in Lesson 1.2.
Center Line
Project Lead The Way, Inc.
Copyright 2007

7. The rest of this PowerPoint will be used in Unit 2.
Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
The rest of this PowerPoint will be used in Unit 2.
Project Lead The Way, Inc.
Copyright 2007

8. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Section Lines: Lines are used to define where there is material after a part of the object is cut away.
Section Line
STOP PRESENTATION: Students have the line conventions needed for the activities in Lesson 1.2.
Section Line
Project Lead The Way, Inc.
Copyright 2007

9. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Short-Break Line
Short-Break Line: A freehand drawn line that shows where a part is broken to reveal detail behind the part or to shorten a long continuous part.
STOP PRESENTATION: Students have the line conventions needed for the activities in Lesson 1.2.
Project Lead The Way, Inc.
Copyright 2007

10. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Dimension Lines: Lines that are used to show distance.
Arrows are drawn on the ends to show where the dimension line starts and ends.
The actual distance is usually located in the middle of this line to let you know the distance being communicated.
Understanding Line types and when to use them will help your sketches look cleaner and more professional.
Dimension Line
Dimension Line
Project Lead The Way, Inc.
Copyright 2007

11. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Extension Lines: Lines used to show where a dimension starts and stops on an object.
Used with dimension lines to properly dimension an object.
The line is 1/16” away from the part as to not get confused with the object lines.
Understanding Line types and when to use them will help your sketches look cleaner and more professional.
Extension Line
Extension Line
Project Lead The Way, Inc.
Copyright 2007

12. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Long-Break Line
Long-Break Lines: Used to shorten very long objects that do not change in detail.
The line is usually represented as a jagged cut or break.
Understanding Line types and when to use them will help your sketches look cleaner and more professional.
Project Lead The Way, Inc.
Copyright 2007

13. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Leader Line
Leader Lines: Leader lines are used to show dimensions of arcs, circles and to help show detail.
Leader Line
Project Lead The Way, Inc.
Copyright 2007

14. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Line Conventions
Though these standards relate to technical drawing, which is far more precise than freehand sketching, their conventions should be used as a guide when sketching.
Project Lead The Way, Inc.
Copyright 2007

15. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Precedence of Lines
When sketching complex objects, different line types will often overlap each other. Therefore, line precedence must be exercised.
Project Lead The Way, Inc.
Copyright 2007

16. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Precedence of Lines
The following are rules that govern line precedence in sketches and technical drawings.
Object lines take precedence over hidden and center lines.
Hidden lines take precedence over center lines.
Cutting plane lines take precedence over all others.
This will make more since to the students when they do the multiview sketch activities
Project Lead The Way, Inc.
Copyright 2007

17. Precedence of Lines Object lines take precedence over
Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Precedence of Lines
Object lines take precedence over
the hidden lines.
An object line here takes
precedence over the center line.
You may want to save this slide until you start multiview sketch activity.
Project Lead The Way, Inc.
Copyright 2007

18. Line Conventions
Design and Drawing for Production
Unit 1 – Lesson 1.2 – Intro to Technical Sketching
Precedence of Lines
An object line here takes
precedence over the hidden line.
Object lines take precedence over the center lines you would see from the hole.
Object lines take precedence over the hidden lines you would see from the slot cut out in top view.
An object line here takes
precedence over the center line.
Project Lead The Way, Inc.
Copyright 2007