• Working drawing- drawing from which a part can be produced
• Must be a complete set of instructions so the part can produced without provided further information to the fabricator
• Consists of:
• Views necessary to explain the shape
• Dimensions needed for manufacture
• Required specifications (such as material and finish)
• Additional information (such as drawing #, date, part name(s), drafter’s name, etc.)
• Detail drawing- information/drawing of individual part(s); shown on separate sheets or grouped on one sheet
• Assembly drawing-information on how parts will be assembled

• Dimension- a numerical value expressed in appropriate units of measure and use to define the size, location, orientation, form, or other geometric characteristic of a part
• Given on drawings by extension lines, dimension lines, arrowheads, figures, notes, and symbols

 

Basic Rules for Dimensioning

• Dimension in the view where the feature appears true size and shape (i.e. the view that BEST shows the characteristic contour or shape of the object
• Place dimension between views when possible
• Place the dimension line for the shortest length, width, or height nearest to the object- therefore, longest dimension will be furthest from the drawing
• Only one system of dimensions (unidirectional or aligned) should be used on a drawing
• Dimensions should not be repeated in other views
• Dimensions should be completed so there is full definition of each part feature
• Each dimension should have a tolerance (except dimensions specifically identified as reference, maximum, minimum, or stock size)

 

Reference Dimensions: dimension shown for information only- reference dimensions are enclosed in parentheses

DIMENSIONING METHODS

• Choice of dimensioning methods will depend on how the part will be produced or whether the part is intended for mass production or unit production

 

Rectangular Coordinate Dimensioning: dimensions for location, size, and location are placed parallel or perpendicular to reference axes or datum planes that are perpendicular to one another

Chain Dimensioning: places dimensions in a line from one feature to the next

• Use DIMCONTINUE
• May result in an undesirable accumulation of tolerances

 

Datum or Baseline Dimensioning: dimensions originate from a common point or line

• In AutoCAD, use DIMBASELINE or QDIM

 

Arrowless dimensioning

• AutoCAD refers to arrowless dimensioning as ordinate dimensioning
• Use QDIM or DIMORDINATE
  

Tabular Dimensioning: A form of arrowless dimensioning in which dimensions to features are shown on a table

 

Chart Dimensioning: a unidirectional, aligned, arrowless, or tabular dimensioned drawing used when dimensions change values

 

Polar Coordinate Dimensioning: method of indicating the position of a point, line, or surface by means of a linear dimension and angle (other than 90 degrees)

• commonly used in circular planes or circular configurations of features

Chordal Dimensioning: used for the spacing of points on the circumference of a circle relative to a datum, where manufacturing methods indicate that this method will be convenient