Wednesday, February 16, 2011

Auxiliary View Notes

Definition
  • secondary view used to show true size and shape (TSS) of a surface that shows foreshortened in all traditional views
***A SURFACE IS TSS WHEN ITS EDGE IN THE NEXT VIEW IS PARALLEL TO THE FOLD LINE

*****SKIP VIEW, MEASURE BACK

Tolerance Notes

It is necessary today to hold precise tolerances to insure the interchangeability of parts
It's the process of determining the smount a dimension can vary from it's theorectical size
  • Basic Size
    • the exact theoretical size of a dimension
  • Tolerance
    • the amount a dimension can vary from basic size
  • Feature
    • used to identify the geometry of the drawing being referenced
  • Limits
    • the maximum and minimum allowable size
  • Allowance
    • the limits where the smallest clearance or largest interference occurs. Measured at MMC
Styles
  • Limit Dimensioning
  • Deviation Dimensioning
  • Symmetrical Dimensioning
MMC
  • (Maximum Material Condition)
    • The limit of a dimension where the max material is left on the part
LMC
  • (Least Material Condition)
    • the limit of a dimension where the least amount of material is left on the part
Type of Fit
  • Clearence (Running and Sliding Fit)
    • all dimension combos will produce clearence between parts
  • Interference
    • all combos of dimensions will produce a force fit
  • Transitional
    • different combos of dimensions will produce different kinds of fits

Dimension Notes

ANSI - American National Standards Institute
  • organization that established standards
  • not arbitrary rules
  • standard way of posistioning dimensions
Why?
  • describes size
  • locate details on an object
Rules
  • Should be for the convience of person reading the drawing
  • no calculations neceessary
  • no duplications
  • 1st dimension line should be 3/8" from object line
  • no gap between line and center line
  • leader scale should equal your dimension
Leaders
  • arrow to edge
  • dot to surface
  • 1/4" tail
  • cross as few lines as possible
  • any angle except horizontal or verticle
  • do not pass them through corners
  • short as possible
Linear Dimensions
  • ALWAYS HAVE HEIGHT, WIDTH, AND DEPTH
  • dont't dimension from a hidden line if possible
  • locate from a common corner
  • smallest dimension closet to part
Angle Dimensions
  • use degree symbol (%%D)
  • drawn at same angle as object being dimensioned
Circle Dimensions
  • ARC always dimensioned with radius
  • CIRCLE always dimensioned with diameter (%%C)
  • cylinder gets dimensioned in the side view
  • hole gets dimensioned where it shows
Ordinate Dimensions
  • use distances on the x and y coordinates
  • relative from the origin (0,0)
  • UCS - user coordinate system
  • move UCS
    • Type "UCS"
    • Type "M"
    • Click where you want the origin
Counterbore & Countersink
  • Underline
    • Type "%%U"
  • Plus/Minus Sign
    • Type "%%P"
  • Counterbore
    • bolt head or scre flush with surface
  • Countersink
    • bolt or screw flush with surface