Chapter 10 continued Dimensioning and Tolerancing
Feb 23, 2016
Chapter 10 continuedDimensioning and Tolerancing
General Notes Relate to the entire part or drawing as
a whole Located next to the title block
Notes:1. Material specs2. Units3. General tolerances4. Finish specs5. Etc.
Delta Notes
Refer to a specific area of the part Note is numbered (usually located
with general notes by title block)
Local Notes
Applied to a specific area of the part by a leader
All text on drawings to be capitol letters
Dimensioning SystemsThe manner of which dimensions are
applied to drawings for different applications.
Selected based on:▪ How the part will be manufactured▪ What features of the part are important based on
its function▪ How many features are on the part▪ The general shape of the part
Systems can be combined to better dimension relationships of features
Unidirectional Dimensioning
all text is horizontal and read from the bottom of the sheet.
Aligned Dimensioning
all text is aligned with the dimension lines
Horizontal dimensions are read from the bottom
Vertical dimensions are read from the right side
Rectangular Coordinate Dimensioning (10.61)
Dimensioning linear dimensions to locate features from planes, centerlines and center planes
Arrowless Dimensioning (fig 10.14)
Also called Ordinate and Rectangular Coordinate without Dimension Lines
Dimensions shown as extension lines only
Horizontal and vertical dimensions measured from common locations (origin labeled as 0.00)
Size dimensions for holes given in a table
Tabular Dimensioning (fig 10.15) Size and locations given as x, y, z
coordinates Dimensions shown in a table Features to be shown in table are
labeled with letters
Chart Drawing (fig 10.16)
Multiple parts dimensioned on one drawing Dims common to all parts are placed on the
drawing, dims that differ are placed in a table Used for parts that have the same shape but
different dimensions Differences between parts can be dimensional
or something as minor as a color difference Cuts down on the number of drawings Also used in catalogs for ordering parts
Chain Dimensioning (fig 10.24) Also called point to point Dimensions from one feature to the
next Causes tolerance buildup
Datum Dimensioning (not in book)
Each dimension is measured from a common edge
Very commonly used on engineering drawings
Commonly combined with chain dimensioning
Polar Coordinate Dimensioning (10.62)
Use of angular dimensions to locate feature
Typically on round parts
Dimensioning Symmetrical Objects
Part must be completely symmetrical about a centerline
Can show entire view or partial view Must show symmetry symbol on
centerline
Dimensioning FeaturesAngular Surfaces
Can be dimensioned by:
Dims at both end of the angled surface
Dim at one end and angular dim
Flat taper note
ChamfersChamfer-a slight surface angle to relieve
sharp corners or create lead in on a part that will be inserted into a hole.
45 ˚ chamfers can be dimensioned with a note 3X45˚ or 3X3 All other angles require normal dimensioning
Conical Taper
Dimensioning a cylindrical object that changes diameter
Dimensioned in a view where it appears as a triangle