Dimension Notes

American National Standards Institute
   Organization that establishes Standards
   Not arbitrary rules

Why we dimension
   Describe Size
   Lise details

Basic rules of dimensioning
   Should be dimensioned for connivance of reader
   No calculations necessary
   No duplications
   Shouldn't be closer than 3/8in of an object line

Dimension Lines Should Be
   With lines and symbols inside extension lines
   lines outside, symbols outside if necessary

Extension Lines
   Extends for the object
   No gap from the center line

Leaders
   Leader scale= Dimension scale
   circle, notes,other details
   Arrow to edge dot to surface
   Cross few lines as possible

Linear Dimensions
   3 big dims
   In between views if possible
   Locate from common corner
   Smallest dimension closest to object

Angle dimensions
   Drawn at same angle as object being dimensioned
   Use Degree Symbol

Finished Structure
   check mark

Counter bore : Used when a bolt or cap head screw is required to sit flush  with or below the level of the surface

Counter sink:  Allows screws to sit flush

Auxiliary Views

Some times you need more then three views to tell the whole story.

Auxiliary: Secondary view used to show true size and shape (TSS) of a surface that's for shortened in all traditional views.

TSS: A surface is TSS when its edge in the next view is parallel to the fold line.

How to: Skip a view, measure back.

Tolerance Notes

Tolerances are necessary today to hold precise tolerance to insure  interchangeability.

Definitions:
Toleranceing-Determining the amount of a dimension the object can vary from its theoretical size.
Basic Size: exact theoretical size of a dimension.
Tolerance:Amount a dimension can vary from the basic size.
Feature: Identify geometry of the drawing being referenced.
Limits:The max and minimum of allowable size.
Allowance:Limits where the smallest clearance or largest interference occurs measured at mmc.
MMC:Maximum material condition.
LMC: Least material condition.
Clearance:All dimension combos produce clearance between parts
Interference fit: Force fit
Transitional: Different fits


Tolerance Styles:

.Limit Dimensioning
plus/minus(devation)
Symetrical