1. Teknologi Dan Rekayasa
TECHNICAL DRAWING

2. BASIC RULES OF DIMENSIONING
Objective :
After studying this lesson, the students should be able to :
1. explain the basic rules of dimensioning
2. apply the basic rules of dimensioning on the technical drawing
Teknologi dan Rekayasa

3. BASIC RULES OF DIMENSIONING
Dimensioning is accomplished according three different method. First the principal dimensions are required (length, width and thickness), to enable material corresponding to the basic shape of the component to be obtained from the stores.
These dimensions are termed :
Overall dimensions
Progressive dimensions
Chain dimensions
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4. Overall dimensions
These serve primarily for dimensioning the overall length, width, height or diameter.
5 thick 20
Ø 25 55 25 4

5. Progressive dimensions
These method is used where dimensions are given from definitive datum surfaces or datum edge. 45 50
Datum edge
Ø 25
Ø 10 5 10 10 15
Datum edge
These datum surfaces (datum line) must first be machined (filled, turned, etc). The dimensions can than be built up step by step. 5

6. Chain dimensions
This method is used where a series of associated dimensions, such as, for example, the width of slots or collars and their position, and the width a number of splines. 10 5 5
NOTE :
Always enter the dimension for the slot width on one view
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7. Chain dimensions
If these three methods of dimensioning are combined, they provide a complete system of dimensions. 5 50
Ø 25
Ø 22
Ø 10
Ø 15 20 45 5
5 thick 25 5 15 10 10 55
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8. Chain dimensions
Dimensions of less than 10 mm are indicated with the arrows outside. Those greater than 10 mm with the arrows inside. If several dimensions less than 10 mm occur in a row (dimension chain), Dots can be used instead of arrows. 5 10
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9. RULES FOR DIMENSIONING
1. To place of dimension line.
Right
Wrong
2. To insert chain dimension.
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10. RULES FOR DIMENSIONING
3. To insert parallel dimension.
4. To insert combined dimension.
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11. RULES FOR DIMENSIONING
5. To insert the dimension in line
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12. RULES FOR DIMENSIONING
6. To insert the dimension with coordinates
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13. RULES FOR DIMENSIONING
7. To insert the dimension in the drawing arrangement
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14. THE END
Teknologi dan Rekayasa