Lesson 7.1 Dimensioning Standards

Lesson 7.1 Dimensioning Standards

Dimensioning Standards Introduction to Engineering Design 2012 Project Lead The Way, Inc. Dimensioning Standards In order for the drawings to be dimensioned so that all people can understand them, we need to follow standards that every company in the world must follow. Standards are created by these

organizations: ANSI ISO MIL DOD DIN JIS CE N

Standards Institutions ANSI - American National Standards Institute. This institute creates the engineering standards for North America. ISO - International Organization for Standardization. This is a worldwide organization that creates engineering standards with approximately 100 participating countries.

Standards Institutions The United States military has two organizations that develop standards. DOD - Department Of Defense MIL - Military Standard Standards Institutions DIN - Deutsches Institut fr Normung. The German Standards Institute created many standards used worldwide, including the standards for camera film.

JIS - Japanese Industrial Standard. Created after WWII for Japanese standards. CEN - European Standards Organization. Dimensioning Methods Dimensions are represented on a drawing using one of two systems, unidirectional or aligned. The unidirectional method means all dimensions are read in the same direction.

The aligned method means the dimensions are read in alignment with the dimension lines or side of the part, some read horizontally and others read vertically. Dimensioning Methods Unidirectional Aligned

Dimensions are placed so that they can be read from the bottom of the drawing sheet. This method is commonly used in mechanical drafting. Dimensions are placed so the horizontal dimensions can be read from the bottom of the drawing sheet and the vertical dimensions

can be read from the right side of the drawing sheet. This method is commonly used in architectural and structural drafting. Linear Dimensioning Chain Dimensioning Dimensioning from feature to feature Common dimensioning technique Chain Dimensioning Examples

METHOD 1 Dimension from feature to feature across entire part Manufacturing inaccuracies can accumulate METHOD 2 Dimension from feature to feature except omit one partial dimension

in the chain Dimension overall length/width/height to limit manufacturing inaccuracies Preferable chain dimensioning method Datum Dimensioning Datum Dimensioning Dimensioning from a single point of origin called a DATUM

Reduces dimensional deviations in manufactured parts because each size/location dimension is referenced to a single point Datum Dimensioning Dimensioning Angles Angled surface may be dimensioned using coordinate method to specify the two location distances of the angle.

Angled surfaces may also be dimensioned using the angular method by specifying one location for distance and the angle. Coordinate Method Angular Method

Recently Viewed Presentations