2014年12月3日星期三

Dimensioning and Tolerancing Practices

1. Apply the standard dimensioning practices for mechanical drawings. pp. 490-493

2. Differentiate between current ASME standards and past practices for dimensioning. pp. 494-499

3.   Apply English and metric tolerances to dimensions. pp. 506-520

4.   Calculate standard tolerances for precision fits. pp. 510-511


5.   Apply tolerances using the basic shaft and basic hole systems. pp. 510-519



1.   How are concentric circles best dimensioned?
In their rectilinear view. p444

2.   Sketch the symbols for diameter, radius, depth, counterbore, countersink, and square.

3.   Where are these symbols placed with respect to their numerical values?
Before. p444

4.   What is the primary difference between counterbore and spotface?
Depth of the counterbore. p444

5.   When is a small cross required at the center of a radius?
When the arc is not clearly defined as being tangent to other dimensional features. p442

6.   Define the depth of a blind hole.
It is the depth of the full diameter, not to the point. p444

7.   When are angled extension lines used? Sketch an example.
When space is limited. p441.

8.   When should extension lines be broken?
When passing through an arrowhead. p444

9.   How is a reference dimension identified?
It is enclosed in parentheses. p437

10. How can you tell if a dimension is out of scale (without measuring the drawing)?
The dimension value is underlined. p444

11. Write a note showing that a .25-inch-deep, .875-inch-diameter hole is to be repeated six times.

12. When is an arc dimensioned with a diameter, and when is one dimensioned with a radius?
A radius will have an 'R' preceding the dimension values whereas a diameter will have an 'ø' preceding the dimension value. p446

13. When should the word “drill” replace the word “diameter” when dimensioning a hole?
Never, according the current ASME standards. p446

14. What is the proper proportion of width to length of arrowheads?
Three times longer than they are wide. p437

15. What is the difference between limit dimensioning and plus and minus dimensioning?
Limit dimensions specify the maximum and minimum sizes as part of the dimension. With plus and minus dimensions, the basic size is given, followed by a plus/minus and a tolerance value. p457. p460

16. What is the term for the theoretical size of a feature?
The basic size. p459

17. Compare the thickness of dimension lines to object lines.
They are thinner. p446

18. Compare the thickness of dimension lines to extension lines.
They are the same. p446
19. If two dimensioning guidelines appear to conflict, which guideline should be followed?
Which ever method most clearly communicates the size information will prevail. p451
20. Write a definition of what Rule 1 means for a drawing of a flat washer with a 0.500 diameter ID, 1.000 diameter OD, and a thickness of 0.062. Use a tolerance of plus or minus 0.005.

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