The Mechanicals

  Limit  fit & Tolerance : Unilateral tolerance :variation is only one direction Bilateral tolerance : variation on both side  Fundamental deviation: basic size Tolerance = upper limit - lower limit :Permissible limit of variation for manufacturing is assigned to parts for manufacturing purpose as boundary of acceptable build.  Basic size : Nominal diameter of shaft or hole it is same for both Fit : it is clearance between two mating parts, it can be determined by whether the parts move, temporary joint  ,permanent joint. Clearance fit : Hole is larger than shaft. Transition fit : Hole is fractionally smaller than shaft. Interference fit : Hole is smaller than shaft. Functional dimension : have to be machined and fit  with other mating parts. Drilling :  unilateral Dimension  BIS (Bureau of International Standard) Grade of Tolerance :18 Fundamental tolerance : 25 BSI (British standard System) ...