1. Line Conventions

2. Line Conventions
Lines of varying style and thickness used communicate an object’s geometry.

3. Line Conventions Used in technical drawings
Technical Drawings – Detailed drawings that contain all the information necessary to produce the part.

4. Construction Line
Very lightly drawn lines used to define size and shape.

5. Object Line
Thick and dark
Define the object

6. Hidden Line
Show interior detail not visible from the outside of the part

7. Center Line Define the center of arcs, circles, or symmetrical parts
Half as thick as an object line

8. Section Line
Define where material is cut away

9. Short-Break Line Freehand drawn line
Presentation Name
Course Name
Unit # – Lesson #.# – Lesson Name
Short-Break Line
Freehand drawn line
Shows where part is cut away to reveal internal detail

10. Dimension Line Shows distance Arrows on ends to show start and end
Presentation Name
Course Name
Unit # – Lesson #.# – Lesson Name
Dimension Line
Shows distance
Arrows on ends to show start and end
Actual distance is located in the middle

11. Extension Line Shows where a dimension starts and stops
Presentation Name
Course Name
Unit # – Lesson #.# – Lesson Name
Extension Line
Shows where a dimension starts and stops
Line starts 1/16” away from part to avoid confusion with object lines

12. Long-Break Line Shorten very long objects when geometry is uniform
Presentation Name
Course Name
Unit # – Lesson #.# – Lesson Name
Long-Break Line
Shorten very long objects when geometry is uniform

13. Leader Line Show dimensions of arcs, circles and detail
Presentation Name
Course Name
Unit # – Lesson #.# – Lesson Name
Leader Line
Show dimensions of arcs, circles and detail

14. Precedence of Lines
Complex drawings may require different line types that overlap.

15. Precedence of Lines Examples
Object line has precedence over hidden lines
Object line has
precedence over center line

16. Rules of Line Precedence
Object lines take precedence over hidden and center lines
Hidden lines take precedence over center lines
Cutting plane lines take precedence over all others