What is required for the accuracy of angle milling setups?

Using a sine bar is essential for achieving accurate angle milling setups due to its ability to precisely set the workpiece at a specific angle relative to the milling machine's table. The sine bar utilizes the sine principle of trigonometry, allowing the operator to easily calculate and measure the angle required for the milling operation. By placing the sine bar under the workpiece and adjusting it to an appropriate height, the sine bar's precise angles can be utilized to achieve the desired angle of cut, ensuring that the finished workpiece meets the correct specifications.

In comparison to other tools mentioned, a combination set provides versatility for various measuring tasks, but it does not inherently provide the same level of precision specifically for angle setups like a sine bar does. Adjustable parallels serve the purpose of providing uniform height adjustments but lack the trigonometric capacity to set angles accurately. A machinist square is essential for ensuring the workpiece is square to a surface, but it does not facilitate angled setups needed for angle milling. Each alternative serves a specific function, but the sine bar stands out for its unique capability in securing precise angled cuts during milling.