Introduction to Dimensioning Introduction to Engineering Design © 2012 Project Lead The Way, Inc.

The part depth is 2” but the orthographic drawing Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Rule 1: Dimensions should reflect actual size of the object, not the scaled size. The part depth is 2” but the orthographic drawing measures 0.5” with a ruler. What do you record on the blue print 2” or 0.5”? 2.0 ? 2.0

Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 2. Always include overall dimensions on an object’s height, width, and depth. Overall dimensions should be placed the greatest distance away from the object so that intermediate (in-between) dimensions can nest (fit together) closer to the object. (Bigger dimensions outside of smaller dimensions)

2. Always include overall dimensions on an object’s height, width, and depth. Overall dimensions should be placed the greatest distance away from the object so that intermediate (in-between) dimensions can nest (fit together) closer to the object. (Bigger dimensions outside of smaller dimensions)

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 3. Include all dimensions necessary to produce or inspect the part. Incorrect ? ? Project Lead The Way, Inc. Copyright 2007

3. Include all dimensions necessary to produce or inspect the part. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 3. Include all dimensions necessary to produce or inspect the part. Project Lead The Way, Inc. Copyright 2007

Incorrect 4. Do not include unnecessary dimensions. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 4. Do not include unnecessary dimensions. Dimensions should NOT be duplicated or the same information given in two different ways. DUPLICATED Incorrect Project Lead The Way, Inc. Copyright 2007

Incorrect 4. Do not include unnecessary dimensions. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 4. Do not include unnecessary dimensions. Do not include chain dimensions that add up to a given overall dimension. Provides the same information in two different ways. Incorrect Project Lead The Way, Inc. Copyright 2007

4. Do not include unnecessary dimensions. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 4. Do not include unnecessary dimensions. Important Note: In the case of chain dimensions, in general, you do not need to know the measurement of every smaller dimension in a chain that contributes to an overall dimension if the overall dimension is given. At least one of the dimensions should be omitted to avoid over dimensioning. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 5. Dimensions should be attached to the view that best shows the contour (the shape) of the feature to be dimensioned. Incorrect Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 5. Dimensions should be attached to the view that best shows the contour of the feature to be dimensioned. Project Lead The Way, Inc. Copyright 2007

5. Dimensions should be attached to the view that best shows the contour of the feature to be dimensioned.

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 6. A dimension should be attached to only one view; for example, extension lines should not connect two views. Incorrect Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 6. A dimension should be attached to only one view; for example, extension lines should not connect two views. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 7. Whenever possible, locate dimensions between adjacent views. Incorrect Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 7. Whenever possible, locate dimensions between adjacent views. (in the middle) Project Lead The Way, Inc. Copyright 2007

Incorrect 8. Avoid dimensioning to hidden lines. 0.75 0.75 Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 8. Avoid dimensioning to hidden lines. Incorrect 0.75 0.75 Project Lead The Way, Inc. Copyright 2007

8. Avoid dimensioning to hidden lines. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 8. Avoid dimensioning to hidden lines. 0.75 Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 9. Do not place dimensions on the object unless it is absolutely necessary. Incorrect Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 9. Do not place dimensions on the object unless it is absolutely necessary. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 10. Do not cross a dimension line with another dimension line or with an extension line. (Extension lines can cross if needed, but try not to) Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 10. Do not cross a dimension line with another dimension line or with an extension line. (extension lines can cross if needed, but try not to) Project Lead The Way, Inc. Copyright 2007

Extension lines can cross if needed but try not to Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances Extension lines can cross if needed but try not to Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 11. Avoid crossing dimension or extension lines with leader lines. Incorrect Project Lead The Way, Inc. Copyright 2007

11. Avoid crossing dimension or extension lines with leader lines. Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 11. Avoid crossing dimension or extension lines with leader lines. Ø 0.50 THRU Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 12. Leader lines point toward the center of the feature and should not occur horizontally or vertically. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 13. Dimension numbers should be centered between arrowheads, except when using stacked dimensions or if they cant fit between the extension lines Incorrect 0.50 Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 13. Dimension numbers should be centered between arrowheads, except when using stacked dimensions, and then the numbers should be staggered or if they cant fit between the extension lines Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 14. In general, a circle is dimensioned by its diameter and an arc by its radius. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 15. Holes should be located and sized in the view that shows the feature as a circle. Incorrect Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 15. Holes should be located and sized in the view that shows the feature as a circle. Project Lead The Way, Inc. Copyright 2007

Dimension Guidelines Introduction to Engineering Design Unit 2 – Lesson 2.2 – Dimensions and Tolerances 16. Holes are located by their centerlines, which may be extended and used as extension lines. Project Lead The Way, Inc. Copyright 2007

References Bertoline, G. (2003). Technical graphics communication. (3 ed.). Boston, MA: McGraw-Hill. Giesecke, F. [et al.] (1991). Technical drawing. (9 ed.). New York, NY: Macmillan Pub. Co. Madsen, D., Folkestad, J., Schertz, K., Shumaker, T., Stark, C., & Turpin, J. (2002). Engineering drawing and design. (3 ed.). Albany, NY: Delmar Thomas Learning.