Sine bar calculator finds the gauge block stack height needed under one end of a sine bar to set a precise angle for inspection or machine setup.
Find the gauge block stack height needed under one end of a sine bar to set a precise angle.
Stack height = sine bar length x sin(angle). This is the height of gauge blocks to place under the roller at one end while the other end rests on the surface plate or fixture.
How it works
A sine bar sets an angle by lifting one end a calculated amount over a known length, so the angle is defined entirely by the ratio of stack height to bar length, the same relationship as the opposite and hypotenuse of a right triangle.
FAQ
Why use a sine bar instead of a protractor? A sine bar paired with gauge blocks can hold an angle to a few arc-seconds of accuracy, far tighter than a mechanical protractor or digital angle finder.
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How it works
A sine bar has rollers a fixed, known distance apart; raising one end on a stack of gauge blocks tilts the bar, and the stack height equals the sine bar’s length times the sine of the desired angle. This is one of the most precise practical ways to set or verify an angle in a machine shop without relying on a protractor’s limited resolution.
FAQ
Why use a sine bar instead of a digital protractor? A properly used sine bar with accurate gauge blocks can hold angular accuracy well beyond what most shop protractors or angle finders achieve, which matters for precision fixture setups, angle inspection, or grinding work.
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