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Dimensioning
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- 5. For Example: 1. Visible 2.Hidden 3. Center
- 6. Heights of Lettersand Numerals
- 8. Dimension Line Extension Lineor Projection line Arrow heads Leader line Elements of Dimensioning (IS: SP46-2003)
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- 12. Example of useof Leader Line
- 13. Diameter symbol –Ø - a symbol which precedes a numerical value, to indicate that the dimension shows the diameter of a circle. Radius symbol – R - a symbol which precedes a numerical value, to indicate that the dimension shows the radius of an arc.
- 14. Types of Dimensioning Locationdimensions Size dimensions Mating dimensions
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- 18. Arrangement of Dimensioning ChainDimension
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- 20. Super imposed RunningDimensions Dimensioning by coordinates
- 21. Rules for Dimensioning Whenthe dimension is less than one, a zero precedes the decimal point. Arrow head should touch the extension line but it never crosses it. Dimension lines are thin lines which are drawn by H-Pencil Dimension lines should be placed outside the object, if possible Extension lines should not crosses the Dimension lines. Extension lines should extend slightly beyond the Dimension line.ie) 3mm. Dimension line should be at a distance of about 10 to 12 mm away from object line. The next successive lines should be with a gap of 10 mm from the first dimension line Dimension lines should be marked only in visible outlines not from the hidden lines.
- 22. Unnecessary Dimensions shouldbe avoided. Dimensions placed in one view should not be repeated in other view. Every dimension should be placed only once. For all views overall dimensions like length, breadth, and height should be marked. Centre lines should not be used as Dimension lines except when centre lines passes through centre of hole. Always place a smaller dimension first and then larger dimensions, so that extension line will not cross the Dimension line.
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- 24. Dimensioning Spheres Dimensioning squareand dimensioning Hexagon Dimensioning Chamfer angle 450 and Dimensioning Chamfer angle other than 450 Dimensioning counter sinks
- 25. EXAMPLE OF CORRECTAND INCORRECT DIMENSIONING
- 26. EXAMPLE OF CORRECTAND INCORRECT DIMENSIONING
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Editor's Notes
- #6 From Bertoline: Figure 2.38 / Pg 42 In engineering and technical drawing, it is important that hidden features be represented, so that the reader of the drawing can clearly understand the object. Thus we need hidden lines to emphasize that those features exist and are hidden in that particular view. We also need center lines to understand how the features defined in the 2D views translate into 3D. NOTE: It must be emphasized that hidden lines and center lines are used only on Orthographic projection drawings, never on isometric drawings Q: Do we need a convention for what line to show if two lines fall on top of each other? A: Yes! Otherwise features which are more important (eg: visible lines) would be overridden by less important features (eg: hidden lines) and the resulting drawing would be interpreted inaccurately. The next slide shows the convention followed.