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