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Dimensioning Standards …..Why are they needed?. To give manufacturers and part fabricators the information they need to create complicated parts. AMERICAN NATIONAL STANDARDS INSTITUTE Organization that oversees products, services, drawing plans, etc. Working Drawing. How are they read?. - PowerPoint PPT Presentation
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Dimensioning Standards…..Why are they needed?
To give manufacturers and part fabricators the information they need to create complicated parts.
AMERICAN NATIONAL STANDARDS INSTITUTE•Organization that oversees products, services, drawing plans, etc
How are they read?
Appropriate units of measure
– Inches– Millimeters
Decimals recommended over fractions of an inch.
Two common systems
Working Drawing
What is wrong with this picture?
With this one?
Importance of standards!
Unidirectional System
Aligned System
Standard Spacing
1/4”1/4”
3/8” 1/16”GAP
Dimension Lines Extension Lines
ArrowheadsArrowheads on dimension lines
– Touch extension lines and are drawn to specific proportion
1/3 of ArrowheadLength
Length
Can be slightly curved
Dimension PlacementWhenever possible, dimensions should be placed between the views to which they relate.
Avoid Preferred
Extension Line ConflictLine conflict should be kept to a minimum.
– Place smallest dimensions closest to the object.
Avoid Preferred
Hidden LinesShould not be used for dimension unless there is no other way.
Avoid Preferred
Circles and CurvesCircles/curves are dimensioned in a number of ways
– depending upon diameter/radius– TYP. = Typical unless noted otherwise
TYP.
Hole NotesSpecial symbols
– simplify dimensioning multiple or complex holes
Cutting Plane Line
Section Lines
