Tolerances As already indicated, tolerance can be defined as the magni­tude of permissible variation of a dimension or other measured or control criterion from the specified value. Tolerances have to be allowed because of the inevitable human failings and machine limi­tations ...

Interchangeability An interchangeable part is one which can be substituted for similar part manufactured to the same drawing.. In earlier times production used to be confined to small number of units and the same operator could adjust the mating components to obtain ...

Let us consider the effect of combining two monochromatic rays of light of different intensities having the amplitudes A1 and A2. If it were possible to combine them in such "a way that the crest of one coincided with the crest ...

Straight Edges These are used for checking the straightness and flatness of parts in conjunction with the surface plates and spirit levels. These may be made of steel or cast iron. Steel straight edges are available up to 2 m length ...

V-BIock These are widely used for workshop and inspection purposes for checking out the roundness of cylindrical workpieces and for marking centres accurately, etc. Generally the angle of V is 90° and these are available in wide variety of shapes. Some­times clamps ...

Cast Iron Surface Plates with Handles (Refer Fig. 2 .44). Brief  Specifications. These Surface Plates are made of close grained high quality iron. Casting strains are eliminated either by natural ageing or by artificial seasoning. Grade A : Handscraped and spotted. Accuracy : ±0.002 ...

Bench Centres Bench centre consists of a rigid cast iron base made from close grained cast iron having minimum hardness of 180 HB (free from distortion, porosity and other casting defects). The base is provided with suitable T-solts for the attachment ...