Actual Fit: The measured difference, subject to measurement uncertainty, before assembly, between the sizes of two mating parts that are to be assembled.
Additional Discussion by Travis R. Wahl
Actual fit is an important attribute to consider for screw thread design since its determining factors directly affect strength, ease of assembly or disassembly, and the likelihood for galling or seizure to occur between both mating components. The Actual Fit is the absolute size difference between two mating parts in an assembly containing threaded components. The Actual Fit is dependent on the screw thread class of fit, surface finish, material variability, and geometric attributes of the thread itself (the type of screw thread profile used, pitch diameters, threads per inch, and so on). The measurement of the actual fit between two threaded components is accomplished by taking the perpendicular distance between the internal and external screw thread flanking surfaces, as shown in the below graphic:
This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. If accuracy is critical, base your
final decisions on the data provided in the root document: ANSI/ASME
B1.7:2006; which is a copyrighted document. To purchase a copy visit
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Original Posting: 3/2/2012
Last Revision: 7/30/2018
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