Wednesday, February 16, 2011

Auxiliary View Notes

  • Sometimes 3 views aren't enough to show all that you need.
  • Auxiliary views are secondary views used to show true size and shape (TSS) of a surface that is not well represented in a traditional view.
  • A SURFACE IS TSS WHEN ITS EDGE IN THE NEXT VIEW IS PARALLEL TO THE FOLD LINE.
  • Skip a view, measure back.

Tuesday, February 15, 2011

Tolerance Notes

  • Necessary to hold tolerances to insure interchangeability of parts.
  • Tolerance is the amount a dimension can vary from its theoretical size.
  • Basic Size is the exact theoretical size of a dimension.
  • Features are used to identify the geometry being referenced
  • Limits are the minimum and maximum allowable size.
  • Allowance is the limit where smallest clearance or largest interference occurs.

Styles:
  • Limits Dimension
  • +/- Dimension
  • Symmetrical Dimension

MMC = maximum material condition (limit of a dimension where the maximum material is left)
LMC = least material condition (limit of a dimension where the least material is left)

Fit:
  • Clearance fit = All dimension combinations produce clearance between parts.
  • Interference fit = All combinations of dimensions will produce a force fit.
  • Transitional fit = Different combinations will produce different fits.

Dimension Notes

  • Height, Length, Width
  • Dimensions are drawn for the convenience of the reader.
  • No calculations should be necessary.
  • Do not double dimension.
  • 3/8 in. from the object line
  • Don't dimension to hidden lines
  • Smallest dimension closest to object

Leaders
  • Leader Scale = Dimension Scale
  • Arrow to an edge
  • Dot to a surface
  • Not horizontal
  • Not vertical

Ordinate Dimension
  • Uses distances via (x, y)
  • Command = UCS, MOVE
Counterbore
  • Used when a bolt needs to sit flush with the level surface.
Countersink
  • Allows a screw to sit flush with a surface.