Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD1 Question of the Day Who created the first practical light bulb? ANSWER: Joseph Swan, an Englishman, created the first practical light bulb in 1878 Thomas Edison perfected and marketed the design a year later

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD2 Dimensioning Goals Understand the principles of good dimensioning practice Apply the standard dimensioning practices for engineering drawings Reference BTG Chapter 7 – Dimensions and Tolerances

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD3 Geometrics The science of specifying and tolerancing shapes and locations of features of on objects

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD4 Geometrics It is important that all persons reading a drawing interpret it exactly the same way. Parts are dimensioned based on two criteria: Basic size and locations of the features Details of construction for manufacturing Standards from ANSI (American National Standards Institute)

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD5 Scaling vs. Dimensioning Drawings can be a different scales, but dimensions are ALWAYS at full scale.

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD6 Units of Measure Length English - Inches, unless otherwise stated  Up to 72 inches – feet and inches over SI – millimeter, mm Angle degrees, minutes, seconds Angle Dimensions

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD7 Dimensioning Terminology

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD8 (.25 in) (.375 in) Dimensioning Standards

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD9 Dimensioning Basic Shapes -Assumptions Perpendicularity Assume lines that appear perpendicular to be 90° unless otherwise noted Symmetry If a part appears symmetrical – it is (unless it is dimensioned otherwise) Holes in the center of a cylindrical object are automatically located

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD10 Dimensioning Basic Shapes Rectangular Prism

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD11 Cylinders Positive Negative Dimensioning Basic Shapes

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD12 Dimensioning Basic Shapes Cone Frustum

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD13 Dimensioning Basic Shapes Circle Pattern Center Lines

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD14 Dimensioning Shows: Size Location & Orientation

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD15 Example Problem Think Individually, then share with the person next to you. - Compare with the other pair at your table What dimensions (size & location) are needed? Where should they be placed?

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD16 Grouping Dimensions Yes No Dimensions should always be placed outside the part

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD17 Staggering Dimensions Put the lesser dimensions closer to the part. Try to reference dimensions from one surface  This will depend on the part and how the tolerances are based.

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD18 Extension Line Practices

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD19 Repetitive Features Use the Symbol ‘x’ to Dimension Repetitive Features

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD20 Symbols for Drilling Operations

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD21 Example Problem What dimensions (size & location) are needed? Where should they be placed? Think Individually, then share with the person next to you. - Compare with the other pair at your table

Fundamentals of Engineering – Honors – ENGR H191 Lecture 16 - AutoCAD22 Assignments Dwg 31 – DIM-1 Fully dimension the objects shown using correct dimensioning practices. (part is fully dimensioned if it is possible to machine it from the dimensions provided) Use Inch Dimensions to the second place (x.xx) Dwg 32 – DIM-2 Fully dimension the objects shown using correct dimensioning practices. Use one-place metric dimensions (x.x) Bring your AutoCAD 2D Book Tomorrow