What ensures that a countersink tool has been adjusted correctly?

To ensure that a countersink tool has been adjusted correctly, checking that five consecutive countersinks are within tolerance is the most reliable method. This approach allows for the identification of consistent results over multiple uses of the tool, thus confirming that it maintains the correct angle and depth.

Adjusting a countersink tool can be affected by various factors such as tool wear, incorrect settings, or inconsistencies in material thickness. By evaluating multiple countersinks in succession, you can effectively rule out variations that might occur due to a single measurement error. Consistency across several countersinks ensures a more accurate adjustment, as it reflects the tool's performance under operational conditions.

Other options like using a single countersink as a reference or relying on a visual inspection alone may lead to inaccurate conclusions about the tool's adjustments. They do not provide the required data to ensure consistent quality across multiple parts. Measuring only the first countersink fails to account for variations that could occur in subsequent operations, which underscores the importance of thorough verification through multiple trials.