Do's And Don'ts Of Dimensioning

Front 1

Each dimension should be given clearly for what reason?

Back 1

So that it can be interpreted in only one way.

Front 2

Dimensions should not be _____ nor should the same information be given in ____ ____ ____ way. No dimension should be given except those needed to produce the part.

Back 2

A) duplicated
B) more than one

Front 3

Dimensions should be given between points or surfaces that have a _______ ______ to each other or that control the location of mating parts.

Back 3

functional relation

Front 4

Dimensions should be given to _________________ in preference to rough surfaces wherever possible.

Back 4

finished surfaces or important centerlines

Front 5

Each dimension should be given clearly for what reason?

Back 5

So that it can be interpreted in only one way.

Front 6

Dimensions should not be _____ nor should the same information be given in ____ ____ ____ way. No dimension should be given except those needed to produce the part.

Back 6

A) duplicated
B) more than one

Front 7

Dimensions should be given between points or surfaces that have a _______ ______ to each other or that control the location of mating parts.

Back 7

functional relation

Front 8

Dimensions should be given to _________________ in preference to rough surfaces wherever possible.

Back 8

finished surfaces or important centerlines

Front 9

Dimensions should be given so that it will not be necessary for the machinist to __________.

Back 9

calculate, scale, or assume any dimensions

Front 10

Dimension features in the view where the feature's shape is best shown.

Back 10

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Front 11

Dimensions should be placed in the views where the features dimensioned are shown true shape.

Back 11

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Front 12

Dimensioning to hidden lines should be avoided wherever possible.

Back 12

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Front 13

Dimensions should not be placed on a view unless clarity is promoted and long extension lines are avoided.

Back 13

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Front 14

Dimensions applying to two adjacent views should be placed between views, unless clarity is promoted by placing some of them outside.

Back 14

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Front 15

The longer dimensions should be placed outside all intermediate dimensions so that dimension lines will not cross extension lines.

Back 15

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Front 16

In machine drawing, all unit marks should be omitted, except when necessary for clarity.
EX 1" Valve

Back 16

repeat

Front 17

Don't let people assume location of a feature, be sure to give a location dimension, unless it is centered. If it is centered be sure to mark the centerline.

Back 17

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Front 18

A dimension should be attached to only one view, not to extension lines connecting two views.

Back 18

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Front 19

Detail dimensions should line up in chain fashion.

Back 19

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Front 20

A complete chain of detail dimensions should be avoided; it is better to omit one. Otherwise reference overall dimension by enclosing it within parentheses.

Back 20

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Front 21

A dimension line should never be drawn through a dimension figure. A figure should never be lettered over any line of the drawing. The line can be broken if necessary.

Back 21

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Front 22

Dimension lines should be spaced uniformly throughout the drawing. They should be at least ____ from object outline and ____ apart.

Back 22

a)10mm
b)6mm

Front 23

No line of the drawing should be used as a dimension line or coincide with a dimension line.

Back 23

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Front 24

A dimension line should never be joined end to end with any line of the drawing.

Back 24

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Front 25

Dimension lines should not cross , if avoidable.

Back 25

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Front 26

Dimension lines and extension lines should not cross if avoidable.

Back 26

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Front 27

When extension lines cross extension lines or visible lines, no break in either line should be made.

Back 27

repeat

Front 28

A centerline may be extended and used as an extension line, in which case it is still drawn like a centerline.

Back 28

repeat

Front 29

Centerlines should not extend from view to view.

Back 29

repeat

Front 30

Leaders for notes should be straight, not curved, and point to the center of circular views of holes.

Back 30

repeat

Front 31

Leaders should slope at 45, 30, or 60 degrees with horizontal, but may be made at any convenient angle except vertical or horizontal.

Back 31

repeat

Front 32

Leaders should extend from the beginning or the end of a note, with the horizontal "shoulder" extending from mid-height of the lettering.

Back 32

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Front 33

Dimension figures should be approximately centered between arrowheads, except in a stack of dimensions, where they should be staggered.

Back 33

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Front 34

Dimension figures should be about 3 mm high for whole numbers and 6 mm high for fractions.

Back 34

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Front 35

Dimension figures should never be crowded or in any way made difficult to read.

Back 35

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Front 36

Dimension figures should not be lettered over lines or sectioned areas unless necessary, in which case a clear space should be reserved for the dimension figures.

Back 36

repeat

Front 37

Dimension figures for angles should generally be lettered horizontally.

Back 37

repeat

Front 38

Fraction bars should never be inclined, except in confined areas, such as in tables.

Back 38

repeat

Front 39

The numerator and denominator of a fraction should never touch the fraction bar.

Back 39

repeat

Front 40

how should notes should always be lettered on the sheet?

Back 40

Horizontally

Front 41

Notes should be brief and clear, and the wording should be in standard form.

Back 41

repeat

Front 42

Finish marks should be placed on the edge views of all finished surfaces, including hidden edges and the contour and circular views of cylindrical surfaces.

Back 42

repeat

Front 43

Finish marks should be omitted on holes or other features where a note specifies a machine operation.

Back 43

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Front 44

Finish marks should be omitted on parts made from rolled stock.

Back 44

repeat

Front 45

If a part is finished all over what should one do?

Back 45

Finish marks should be omitted and instead use general note finish all over or FAO.

Front 46

A cylinder is dimensioned by giving both its diameter and length in the rectangular view, except when notes are used for holes. A diagonal diameter in the circular way may be used in cases where it increases clarity.

Back 46

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Front 47

Drill sizes should be expressed in decimals, giving the diameter. For drills designated by number or letter decimal size must also be given.

Back 47

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Front 48

In general, a circle is dimensioned by its diameter, but what is an arc dimensioned by?

Back 48

It's radius.

Front 49

Diagonal diameters should be avoided except for very large holes and for circles of centers. They may be used on positive cylinders when clarity is gained.

Back 49

repeat

Front 50

A diameter dimension should always be preceded by what symbol?

Back 50

A circle with a slash through it

Front 51

A radius dimension should always be preceded by ___________. the radial dimension line should have only one arrowhead. It should pass or point through the arc center and touch the arc.

Back 51

The letter R

Front 52

Cylinders should be located by their _______.

Back 52

Centerlines

Front 53

Cylinders should be located in the circular views, if possible.

Back 53

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Front 54

Cylinders should be located by coordinate dimensions in preference to angular dimensions where accuracy is important.

Back 54

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Front 55

When there are several rough noncritical features obviously the same size it is necessary to give only one typical dimension or use a note.

Back 55

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Front 56

When a dimension is not to scale what should be done?

Back 56

Should underscore dimension with a heavy straight line or mark NTS or Not to Scale

Front 57

Mating dimensions should be given correspondingly on both drawings of mating parts.

Back 57

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Front 58

Pattern dimensions should be given in two place decimals or _______.

Back 58

In common whole numbers and fractions to the nearest zero.

Front 59

Decimal dimensions should be used for all machining dimensions.

Back 59

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