What is the radial clearance value for a close fit on a 1/4 inch bolt as given?

• A. 0.250 inch
• B. 0.257 inch
• C. 0.266 inch
• D. 0.0035 inch

Answer: (D)

Radial clearance is the small gap between the bolt and its bore, equal to half the difference between the bore diameter and the bolt diameter. For a close fit, the bore is only slightly larger than the bolt. If the bolt is 0.250 inch and the bore is 0.257 inch, the difference is 0.007 inch. Half of that is 0.0035 inch, which is the radial clearance. The other numbers aren’t clearance values—they are the bolt size (0.250 inch) and the bore size (0.257 inch); a larger bore like 0.266 inch would give a larger clearance (0.008 inch).