Basic Dimensioning Practices

Basic Dimensioning Practices
Sacramento City College EDT 310 EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Practices
Dimensional information includes Size dimensions. Location dimensions. Notes. EDT Chapter 18 - Basic Dimensioning Practices

Size Dimensions Size dimensions provide the size of physical features. A feature is any physical portion or characteristic of a part or object such as: Diameter of holes Width Length Depth EDT Chapter 18 - Basic Dimensioning Practices

EDT 310 - Chapter 18 - Basic Dimensioning Practices
Dimensioning Shapes EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Flat Surfaces
Dimension flat surfaces by giving measurements for each feature. Architectural drafting - show all dimensions. Refer to Figures 18-17, 18-18 EDT Chapter 18 - Basic Dimensioning Practices

Architectural Style EDT Chapter 18 - Basic Dimensioning Practices

Mechanical Style EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Cylindrical Shapes
The diameter and the length can be dimensioned in one view. Use the view where the cylinder appears rectangular. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Cylindrical Shapes
EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Square Features
Dimensioning Square/Rectangular shapes Dimension in views where the length and height are shown. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Square Features

Dimensioning Conical Shapes
Dimensioning Cones and Regular Polygons Conical shapes - dimension two ways: 1. Give the diameters at both ends and the length. 2. Give the taper angle and length. EDT Chapter 18 - Basic Dimensioning Practices

Conical Shapes #1 EDT Chapter 18 - Basic Dimensioning Practices

Conical Shapes #2 EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Regular Polygons
Regular Polygon shapes – Dimension by giving the distance across the flats and the length. EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Location Dimensions Location dimensions provide the location of physical features on the object. Location of holes from end Datum Dimensioning Chain Dimensioning Location of windows/doors in buildings EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Location dimensions are used to locate features on an object. Holes Offsets Location dimensions do not provide size. EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Holes and arcs are dimensioned in the view where they appear circular. Rectangular features are dimensioned to their edges. EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Two types of location dimensioning systems Rectangular coordinates and Polar coordinates EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Rectangular coordinates are linear dimensions used to locate features from surfaces, centerlines or center planes Use DIMLINEAR command. EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Rectangular Coordinate Location Dimensions EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Polar Coordinate Location Dimensions EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions In architectural drafting, windows and doors are dimensioned to their centers on the floor plan. EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions EDT Chapter 18 - Basic Dimensioning Practices

Location Dimensions Polar coordinates uses angular dimensions to locate features from surfaces, centerlines or center planes. Use DIMANGULAR command. EDT Chapter 18 - Basic Dimensioning Practices

Notes EDT Chapter 18 - Basic Dimensioning Practices

Notes Notes Notes give information about individual or specific features on the drawing. Two types Specific Notes General Notes EDT Chapter 18 - Basic Dimensioning Practices

Notes Specific notes Relate to individual or specific features on the drawing. They are attached to the feature with a leader line. General Notes Apply to the entire drawing and Are placed together in one area of the drawing. Exact location depends on sheet size, and industry, company or school practice. EDT Chapter 18 - Basic Dimensioning Practices

Notes EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Standards

Each drafting field uses a different type of dimensioning technique Architectural. Mechanical. Civil. Electronics. EDT Chapter 18 - Basic Dimensioning Practices

Drafters should place dimensions in accordance with company and industry standards. Use the company standard FIRST. When no company standard exists, use industry standards. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning standards are used so an object designed in one place can be manufactured or built somewhere else. EDT Chapter 18 - Basic Dimensioning Practices

ASME Y-14.5M-1994 Dimensioning and Tolerancing Standard emphasized in the textbook. M - means metric. 1994 is the year it was published. ASME is the American Society of Mechanical Engineers. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Formats EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Formats Unidirectional Dimensioning is “Unidirectional” means one direction. All dimension numbers and notes are placed horizontally on the drawing sheet. Numbers are read from left to right when viewed from the bottom of the drawing sheet. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Formats Aligned Dimensioning is Used on architectural drawings. Horizontal dimensions are read horizontally. Vertical dimensions are read vertically from the right edge of the sheet. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Formats EDT Chapter 18 - Basic Dimensioning Practices

Dimension Styles used by Particular Field of Work

Dimensions - Mechanical
Mechanical Field. Uses Unidirectional dimensioning Dimensioning parts. Dimension Characteristics 1. Uses arrowheads for terminators. 2. Dimension line is broken 3. Dimension number is centered inside dimension line. EDT Chapter 18 - Basic Dimensioning Practices

Dimensions - Mechanical

Dimensions - Architectural
Architectural Field. Uses Aligned dimensioning Dimension Characteristics 1. Uses “tic” marks for terminators. 2. Dimension line is unbroken. 3. Dimension number is centered over dimension line. 4. Dimension is aligned with surface. EDT Chapter 18 - Basic Dimensioning Practices

Dimensions - Architectural

Dimensioning practices depend on Product requirements. What are you making? Manufacturing accuracy. Extreme precision vs approximate dimensions. Standards. What dimension standards exist for your industry? Tradition. How has your industry dimensioned in the past? EDT Chapter 18 - Basic Dimensioning Practices

Compare dimensioning practices for: Automobile. (decimal inches) Architecture. (feet, inches, fractions of inch) Microprocessor chip. (1/10,000 to 1/100,000 of an inch Civil. (Miles or kilometers) Each dimension type is appropriate for that discipline. EDT Chapter 18 - Basic Dimensioning Practices

Precision is indicated by decimal places Automobile. (decimal inches) 3 inches vs inches Architecture. feet (???) !! Civil. miles (???) !! Precision must be appropriate for that discipline. EDT Chapter 18 - Basic Dimensioning Practices

The number of decimal places shown on a dimension increases manufacturing costs! Paper weight measurements 3.0000” x ” x ” Vs 3” x 4” x 2” EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Circles EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Circles Circles are normally dimensioned by giving the diameter. Per ASME standard, arcs are dimensioned by giving the radius. AutoCAD lets you dimension a circle or an arc by giving the diameter dimension. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Circles Diameter dimensions are produced by: Picking the Diameter Dimension button on the Dimension Toolbar. OR Picking Diameter in the Dimension pull-down menu. Typing DDI or DIMDIAMTER at the Command: prompt. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Circles When you use the DIMDIAMETER command, a leader line and diameter dimension value are attached to the cursor when you pick the circle or arc. The leader can be dragged to any desired location and length before picking where you want it to be placed. The Mtext, Text and Angle options are available. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Holes EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Holes Holes are dimensioned in the view where they appear as circles. To dimension holes: Give location dimensions to the center and a leader showing the diameter. Use the DIMDIAMETER command to dimension the diameter. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Repetitive Features

Dimensioning Repetitive Features
Repetitive features are dimensioned by: The number of repetitions Followed by an X, a space, and the size dimension. The dimension is then connected to the feature with a leader. Refer to Figure EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Arcs EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Arcs The standard for dimensioning arcs is the radius. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Arcs Use the DIMRADIUS command to place a radius command by: Picking the Radius Dimension button on the Dimension toolbar. OR Picking Radius in the Dimension pull-down menu. Typing DRA or DIMRADIUS at the Command: prompt. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Fillets and Rounds

Dimensioning Fillets and Rounds
Small inside arcs are called fillets Fillets are designed to strengthen inside corners. Small arcs on outside corners are called rounds. Rounds are used to relieve sharp corners Dimension each one individually as arcs or as a general note. See Figure EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Angles EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Angles Coordinate and angular dimensioning are both acceptable for dimensioning angles. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Angles Coordinate dimensioning uses coordinates to specify the length of line segments to start locations of angles. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Angles Angular dimensioning Locates one corner with a dimension and provides the value of the angle in degrees. You can dimension the angle between any two non-parallel lines. EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Curves Where possible, curves are dimensioned as arcs. Where curves are not of a constant-radius, Dimension them to points along the curve using the DIMLINEAR command. See Figure EDT Chapter 18 - Basic Dimensioning Practices

Dimensioning Chamfers
A chamfer is an angled surface used to relieve sharp corners. To dimension chamfers: Show angle and a linear dimension OR Two linear dimensions EDT Chapter 18 - Basic Dimensioning Practices

Basic Dimensioning Practices

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