Sine bar is a accurate instrument for measu-ring angle. Sine bar consist of a rectangular bar made of high quality steel and having steps at the end . A roller is fitted into each step which touch the roller. The Sine bar is specified by the distance between center of two rollers ,i.e. 100 mm , 200 mm , 250 mm and 300 mm . The roller must be of the same diameters. The roller are so fixed that when sine bar is placed on surface plates the sur-face of the bar is exactly parallel to surface plate.
When component is small size-:
For checking the angle of a component of small size a sine bar is set-up at nominal angle on a surface plates by situable combi-nation of the slip gauge . The component to be checked is pressed over the surface of the sine bar. A dial gauge is carried with surface gauge is move along the upper surface of the component.
When component size is large-:
The component is placed over a surface plate. The sine bar is placed over the com-ponent. The heights on the rollers are meas-ured by means of vernier height gauge. A dial gauge is used to check the measuring pressure.
The angle can be found by this formula-:
SINE Ө = H / L
Where, H = Height made by slip gauge.
L = Distance between roller.
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