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Questions and Answers
What is one of the most demanding undertakings when designing parts?
What is one of the most demanding undertakings when designing parts?
Accurate dimensioning
Which organization creates engineering standards for North America?
Which organization creates engineering standards for North America?
Which of the following organizations is involved in standardization worldwide? (Select all that apply)
Which of the following organizations is involved in standardization worldwide? (Select all that apply)
The two methods of dimension representation on a drawing are _____ and _____ systems.
The two methods of dimension representation on a drawing are _____ and _____ systems.
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In the unidirectional dimensioning method, dimensions can be read in multiple directions.
In the unidirectional dimensioning method, dimensions can be read in multiple directions.
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What are the two classifications of dimensions?
What are the two classifications of dimensions?
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What should be avoided according to the dimensioning checklist?
What should be avoided according to the dimensioning checklist?
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What is the requirement for dimensioning circles?
What is the requirement for dimensioning circles?
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Which of these dimensions should be placed outside the part?
Which of these dimensions should be placed outside the part?
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Which of the following organizations is NOT involved in establishing engineering standards?
Which of the following organizations is NOT involved in establishing engineering standards?
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What does ANSI stand for?
What does ANSI stand for?
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What are the two systems of dimension representation on a drawing?
What are the two systems of dimension representation on a drawing?
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Extension lines should cross dimension lines.
Extension lines should cross dimension lines.
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What are the two classifications of dimensions?
What are the two classifications of dimensions?
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The German Standards Institute is known as _____ .
The German Standards Institute is known as _____ .
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What should be done if dimension text does not fit between extension lines?
What should be done if dimension text does not fit between extension lines?
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The military standards are developed by the Department of Transportation.
The military standards are developed by the Department of Transportation.
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What should be extended from the view to indicate edges referenced?
What should be extended from the view to indicate edges referenced?
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Study Notes
Dimensioning Standards
- Accurate dimensioning is crucial for the design process, ensuring comprehension and manufacturability.
- A checklist ensures adherence to basic dimensioning rules, although exceptions may exist for clarity.
Standards Organizations
- ANSI - American National Standards Institute - Sets engineering standards for North America.
- ISO - International Organization for Standardization - Global organization creating engineering standards with over 100 participating countries.
- DIN - Deutsches Institut für Normung - German Standards Institute, responsible for standards like camera film.
- JIS - Japanese Industrial Standard - Established post WWII for Japanese standards.
- CEN - European Standards Organization
- DOD - Department of Defense
- MIL - Military Standard - Develops standards for the US military.
- ANSI/ASME Y14.1 and Y14.5 - International drafting standards for engineering drawings.
Linear Dimensioning Components
- Dimension Text - Identifies the size of the feature.
- Dimension Lines - Lines connecting extension lines to show dimension measurement.
- Arrow Heads - Markers at the ends of dimension lines.
- Extension Lines - Lines extending from the object to the dimension line.
Extension Lines Rules
- Extend 3mm past the dimension line.
- Extend from the view to indicate the edges being dimensioned, directly connected to the dimension line.
- Maintain a 2mm gap from the view to avoid confusion with visible lines.
Dimension Lines Rules
- Horizontal - Aligned when dimensioning slanted surfaces.
- Vertical - For standard dimensions.
- Stacked - Maintain 10mm distance from the view and 10mm apart.
Dimension Text Rules
- Placed in the middle of the line both horizontally and vertically.
- Can be placed outside extension lines if space is limited.
Dimensioning Methods
- Unidirectional - All dimensions are read in the same direction, commonly used with mechanical drafting.
- Aligned - Dimensions are read aligned with the dimension lines or part side, some horizontal, some vertical; commonly used in architectural and structural drafting.
Dimension Types
- Size - Directly related to a feature, identifying its specific size.
- Location - Shows a feature's relationship to another feature within the object.
Dimensioning Checklist:
- Clarity - One interpretation possible.
- Uniqueness - Each feature dimensioned only once.
- Fraction - Dimensions expressed as fractions only.
- Non-crossing - Dimension and extension lines should not overlap.
- All Features - Each feature should be dimensioned.
- Logical Reference - Dimension features referencing a logical point.
- Circles and Arcs - Circles dimensioned with diameters, arcs with radius.
- Centered Extensions - Center lines extended to act as extension lines.
- True Shape - Features depicted with their true shape.
- Adequate Space - Enough space for clear representation.
- No Overlap - Extension lines and object lines do not overlap.
- External Placement - Dimensions positioned outside the part.
- Center Marks - Center lines for all circles and holes.
- Total Object Dimensions - Overall width, depth, and height indicated.
Linear Dimensioning
- Dimensioning from feature to feature.
Dimensioning Standards
- Dimensioning is a demanding aspect of design, with specific rules and practices for accurate representation.
- Standardization ensures clarity and universal understanding across companies and industries.
- Key organizations establishing standards include:
- ANSI (American National Standards Institute) - For North America
- ISO (International Organization for Standardization) - Worldwide
- DIN (Deutsches Institut für Normung) - German Standards Institute
- JIS (Japanese Industrial Standard)
- CEN (European Standards Organization)
- DOD (Department of Defense) and MIL (Military Standard) - for U.S. Military
- ANSI/ASME Y14.1 and Y14.5 are international drafting standards for engineering drawings.
Linear Dimensions
- Linear dimensions consist of four essential components:
- Dimension text
- Dimension lines
- Arrowheads
- Extension lines
Extension Lines
- Extension lines extend 3mm past the dimension line.
- They are extended from the view to indicate the edges being referenced.
- They should have a 2mm gap from the view to avoid confusion with visible lines.
Dimension Lines
- Dimension lines can be horizontal, vertical, or aligned to a slanted surface.
- When stacked, they are spaced 10mm from the view and 10mm apart.
Dimension Text
- If the dimension text cannot fit between the extension lines, it can be placed outside.
- Dimension text is placed in the middle of the line, both horizontally and vertically.
Dimensioning Methods
- There are two primary dimensioning systems: unidirectional and aligned.
- Unidirectional dimensions are read in the same direction, commonly used in mechanical drafting.
- Aligned dimensions are read in alignment with dimension lines or the part's side, allowing for horizontal reading from the bottom and vertical reading from the right side of the sheet, commonly used in architectural and structural drafting.
Types of Dimensions
- Dimensions are categorized as size or location.
- Size dimensions directly indicate the size of a feature.
- Location dimensions define the relationship of a feature to another feature within the object.
Dimensioning Checklist
- Clarity: Each dimension should be clearly written to avoid misinterpretations.
- Avoidance of Repetition: A feature should only be dimensioned once.
- Fractional Dimensions: Dimensions should be in fractions only.
- No Crossing Lines: Dimension and extension lines should not intersect.
- Complete Dimensioning: All features should have dimensions.
- Logical Reference Points: Dimension features or surfaces with logical reference points.
Dimensioning Checklist - continued
- Circle and Arc Dimensions: Circle diameters and arc radii should be dimensioned.
- Center Lines as Extension Lines: Center lines should be extended and used as extension lines.
- True Shape Representation: Dimensions on a view should clearly show the true shape of the feature.
- Adequate Spacing: Sufficient space should be provided to prevent crowding and misinterpretations.
Dimensioning Checklist - even further
- Non-Overlapping Lines: Object lines and extension lines should not overlap.
- External Dimensions: Dimensions should be placed outside the part.
- Center Marks for Circles and Holes: Use center lines or marks on all circles and holes.
- Overall Dimensions: Total width, depth, and height of the object should be specified.
Linear Dimensioning
- Features are dimensioned by referencing them to one another.
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Description
This quiz covers essential engineering dimensioning standards and organizations like ANSI, ISO, and DIN. Understanding these standards is vital for accurate design and manufacturability in various engineering fields. Test your knowledge on the significance and application of these dimensioning guidelines.
