Question 68

The Correct Answer is A **Explanation for Option A (0.0005 inch):** Option A, **0.0005 inch**, represents a very tight unilateral or bilateral tolerance that would typically be applied to a critical mating feature requiring high precision, such as the outside diameter (OD) of a bushing. Bushings are often press-fit or require a precise clearance fit within a housing. For a tight tolerance that ensures proper function and fit (e.g., maintaining concentricity or achieving a precise running clearance), a small tolerance like 0.0005 inch (one-half thousandth) is common and appropriate for a precision machined part like a bushing OD. **Explanation of Incorrect Options:** * **B) 0.002 inch:** While 0.002 inch is a reasonable machining tolerance, it is four times larger than 0.0005 inch. Given the context of a precision bushing OD, 0.002 inch (two thousandths) might be considered too loose if the application requires an extremely tight interference or accurate running fit. While possible, it is less likely to be the *most* appropriate or required tight tolerance compared to 0.0005 inch for a critical dimension. * **C) 0.060 inch:** This tolerance is **0.060 inch** (sixty thousandths) or $\pm 1/16$ inch. This is an extremely large tolerance, typical of general fabrication, rough saw cuts, or non-critical features. It is entirely unacceptable for the OD of a precision bushing, which must fit accurately into another component. * **D) 1.6015 inches:** This value is not a tolerance; it is a **dimension** (a specific size measurement). A tolerance is the allowable variation *from* a nominal dimension (e.g., $\pm 0.0005$ or $1.6000/1.6005$). Therefore, it cannot be the tolerance allowed on the diameter.