1. CHAPTER 6
Lines and Lettering

2. Learning Objectives
Identify the lines found on a given industry drawing
Draw ASME standard lines
Solve engineering given problems
Create ASME standard text
Answer questions related to lines and lettering

3. Lines Must be of a quality that reproduces easily
Dark, crisp, sharp, and of the correct thickness
No variation in darkness
Variation in thickness
Thicker lines stand out clearly
Thinner lines are subordinate

4. Mechanical Drafting Line Standards
ASME Y14.2, Line Conventions and Lettering
Thick lines .02 in. (0.6 mm)
Twice as wide as thin lines
Thin lines .01 in. (0.3 mm)
Half as as wide as thick lines
Military (MIL) standards (STD)
Thick
Medium
Thin

5. ASME Line Conventions

6. ASME Example
[Insert Figure 6.2]

7. Construction Lines Layout Do not represent a specific drawing feature
Not reproduced on the final drawing

8. Visible Lines Object lines, or outlines Visible surfaces or edges
Continuous (solid)
Thick
.02 in. (0.6 mm)
ASME example

9. Hidden Lines Invisible edges
125 in. (3 mm) dashes spaced .06 in. (1.5 mm) apart
Thin
.01 in. (0.3 mm)
ASME example

10. Hidden Line Rules

11. Centerlines Centers of circles and arcs
Center axis of a circular or symmetrical form
Centers in a bolt circle pattern
Paths of motion in a mechanism

12. Centerlines Series of alternating long and short dashes
Long dash .75 to 1.50 in. (19-35 mm)
Spaces between dashes .062 in. (1.5 mm)
Short dash .125 in. (3 mm)

13. Centerlines Extend .125 in. (3 mm) or .25 in. (6 mm) past objects Thin
ASME example

14. Bolt Circle Polar coordinate dimensions
Rectangular coordinate dimensioning

15. Symmetry

16. Extension Lines Establish the extent of a dimension
Begin with a .06 in. (1.5 mm) space from the object
Extend .125 in. (3 mm) beyond the last dimension
Thin
.01 in. (0.3 mm)
ASME example

17. Extension Line Rules
Can cross object lines, centerlines, hidden lines, other extension lines
Should not cross dimension lines
Centerlines become extension lines for dimensioning purposes

18. Dimension Lines Capped on the ends with arrowheads
Broken to provide a space to indicate the length of the dimension
Thin
.01 in. (0.3 mm)
ASME example

19. Leader Lines Leaders Connect a specific note to a feature
Direct dimensions
Symbols
Item numbers
Part numbers

20. Leader Lines 45°, 30°, or 60° angles common
.125 to .25 in. (3-6 mm) shoulder common
Pointing to a line: cap with an arrow
Pointing to a dimension line: no arrow
Pointing inside an object: cap with a .05 in. (1.5 mm) dot

21. Leader Lines
Continuous or hidden
Thin
.01 in. (0.3 mm)
ASME example

22. Leader Line Rules Not cross each other Not excessively long
Not parallel to dimension lines, extension lines, or section lines
Avoid 75°or less than 15°angles from horizontal

23. Arrowheads Terminate dimension lines and leader lines
Cutting plane lines and viewing plane lines
Twice as big as arrowheads on dimension and leader lines
Three times as long as wide
.125 in. (3 mm) long for dimension lines and leader lines
Consistent sizes
Open or filled
ASME example

24. Cutting-Plane and Viewing-Plane Lines
Thick
.02 in. (0.6 mm)
Takes precedence over the centerline
ASME example

25. Cutting-Plane and Viewing-Plane Lines

26. Section Lines Appear in the view of a section
Show where the cutting-plane line cuts through material
45°, 30°, or 60°angles common
Thin
.01 in. (0.3 mm)
ASME example

27. Section Line Rules Equally spaced
ASME minimum space .06 in. (1.5 mm)
Avoid 75°or less than 15°angles from horizontal
Not parallel or perpendicular to object lines
Opposite directions on adjacent parts
Thin parts can be shown without section lining
Omit around text when necessary to have text in a sectional view

28. Section Lines Outline section lining Coded section lines
Thin parts shown without section lining

29. Short Break Lines Shorten the length of a long object or part
Provide a partial view of a feature
Thick
.02 in. (0.6 mm)
ASME example

30. Long Break Lines
Break long distances
Thin
.01 in. (0.3 mm)

31. Phantom Lines Alternate positions of moving parts
Adjacent positions of related parts
Repetitive details
Contour of filleted and rounded corners
Thin
.01 in. (0.3 mm)
ASME example

32. Chain Lines Indicate specified treatment Projected tolerance zone
Alternately spaced long and short dashes
Thick
.02 in. (0.6 mm)
ASME example

33. Stitch Lines Indicate the location of stitching or sewing
Short thin dashes, or
.01 in. (0.3 mm) diameter dots spaced .12 in. (3 mm) apart

34. Lettering
Dimensions
Notes
Titles

35. Lettering Must be of a quality that reproduces easily
Dark, crisp, sharp
CADD text
Font

36. ASME Lettering Standards
ASME Y14.2, Line Conventions and Lettering
Opaque
Clearly spaced
Vertical or inclined
One style
Upper case letters

37. Lettering on Engineering Drawings
Single-stroke Gothic
Vertical uppercase letters
Arial, Century Gothic, RomanS, or SansSerif font

38. Lettering Numbers

39. Inclined and Lowercase Lettering Styles
68°to the right from horizontal
Structural drafting
Civil drafting or maps
Lowercase
Uncommon in mechanical drafting
Engineering specifications

40. Architectural Lettering
Traditional freehand architectural lettering with an artistic flair
StylusBT, ArchiText, CountryBlueprint, or CityBlueprint fonts
United States National CAD Standard (NCS)
SansSerif font

41. Lettering Legibility Background area between letters:
Approximately equal
Individual words clearly separated
Space between two numerals with a decimal point between:
Minimum two-thirds the lettering height
Vertical space between lines of lettering
No more than the lettering height, no less than half the lettering height

42. ASME Letter Heights Sheet Elements Minimum Letter Heights INCH
Drawing Sizes INCH
Letter Heights METRIC (mm)
Drawing Sizes METRIC
Drawing title, sheet size, CAGE Code, drawing number, revision letter in the title block
.24
D, E, F, H, J, K 6
A0, A1
.12
A, B, C, G 3
A2, A3, A4
Zone letters and numbers in borders
All sizes
Drawing block headings
.10
2.5
All other characters

43. Lettering Notes

44. Glossary Cutting-plane lines Font Lettering
Thick lines used to identify where a sectional view is taken.
Font
A complete assortment of any one size and style of letters.
Lettering
All letters and numbers on drawings and related documents.

45. Glossary Polar coordinate dimensions
Uses angular and linear dimensions combined to locate features from planes, centerlines, or center planes.
Rectangular coordinate dimensioning
A system of using linear dimensions to locate features from planes, centerlines, and center planes.

46. Glossary Viewing-plane lines
Thick lines used to identify where a view is taken for view enlargements, for removed views, or for partial views.