What is the typical tolerance range for boring?

• A. +-0.001-0.005 in
• B. +-0.005-0.015 in
• C. +-0.010-0.020 in
• D. +-0.020-0.050 in

Answer: (A)

Boring aims to bring a drilled hole to a precise, true size and roundness by removing small amounts with a boring bar. In most workshop settings, the achievable tolerance for boring a hole is on the order of a few thousandths of an inch, typically around plus or minus 0.001 to 0.005 inches, depending on hole size, tool condition, and machine rigidity. This range reflects what's commonly attainable with standard equipment before finishing operations. Tolerances looser than this would be too imprecise for a bored hole and are more typical of rough drilling or less controlled processes. If tighter control is needed, finishing with reaming or honing can improve the tolerance further. Therefore, the common boring tolerance falls in the 0.001–0.005 in range.