1. Dimensioning Standards…..Why are they needed?
To give manufacturers and part fabricators the information they need to create complicated parts.
AMERICAN NATIONAL STANDARDS INSTITUTE
Organization that oversees products, services, drawing plans, etc

2. How are they read? Working Drawing Appropriate units of measure
Inches
Millimeters
Decimals recommended over fractions of an inch.
Two common systems

3. What is wrong with this picture?

4. With this one?

5. Importance of standards!

6. Unidirectional System

7. Aligned System

8. Standard Spacing 1/4” 1/4” 3/8” Dimension Lines Extension Lines 1/16”
GAP
Dimension Lines
Extension Lines

9. Arrowheads Arrowheads on dimension lines
Touch extension lines and are drawn to specific proportion
Length
1/3 of Arrowhead
Length
Can be
slightly curved

10. Dimension Placement
Whenever possible, dimensions should be placed between the views to which they relate.
Avoid
Preferred

11. Extension Line Conflict
Line conflict should be kept to a minimum.
Place smallest dimensions closest to the object.
Avoid
Preferred

12. Hidden Lines
Should not be used for dimension unless there is no other way.
Avoid
Preferred

13. Circles and Curves Circles/curves are dimensioned in a number of ways
depending upon diameter/radius
TYP. = Typical unless noted otherwise
TYP.

14. Hole Notes Special symbols
simplify dimensioning multiple or complex holes
Cutting Plane Line
Section Lines