Two charters long class mean that the class is valid for both the pitch and major/minor diameters.Small letters represent external threads, while capital letters represent internal threads.It is preceded by a “-” and consists of two or four characters. Class: The class appears after the pitch.If Ph is omitted, the thread has a single start. For this example, the number of starts is 3. Ph must be a multiple of P since the number of starts equals Ph/P. In this case, 2.25 mm is the lead, and 0.75 mm is the pitch. If the “ X P” is omitted, the pitch is defined by the Coase Pitch Series according to ISO-261. Cells with White Background – Values are derived from the description.Cells with Golden Background – Values are derived from the above defaults.Class – 6g for external threads and 6H for internal threads.Pitch– According to the Coarse pitch series.If no characters follow the M and diameter, it means that all the other parameters are according to the default as defined in ISO 965-1: For example, M8 is a thread with a nominal diameter of 8 mm (0.315″). The description always begins with a capital M, followed by the nominal thread diameter in millimeters. They have limited use since they provide data only for the default classes.The values are calculated from the definitions of ISO 965-1.Charts for the allowed range of pitch, major and minor diameters for classes 6H and 6g.Formulas that were used to construct the charts.Recommended Tolerance classes - Charts per tolerance quality and length of engagement.Tolerance fields Charts - Per diameter and pitch.Normal Length of Engagement Chart - Per diameter and pitch.Repairs to more than two adjacent oversize rivets, or replacing more than half the rivets with oversize rivets in any 10 inch length of pattern is prohibited. Repair limitations: The combined oversize rivet hole repairs and oversize countersink repairs should be limited to a maximum of 20 percent of the rivets, or 10 rivets in a single rivet pattern, whichever is less. The term "next larger size" shall be defined as the next larger diameter for the application, but not to exceed 1/32 inch increments for sizes up to 1/4 inch diameter and 1/16 inch increments for sizes above 1/4 inch. Oversize countersinks: When countersinks are enlarged beyond specified tolerances, the next larger size rivet may be used, provided pitch and edge margin design requirements are maintained. Burrs may be removed from rivet holes by chamfering to a depth not to exceed 10 percent of the stock thickness, or 0.032 inch, whichever is less. Mating surfaces should be cleaned before parts are riveted together, all chips, burrs and foreign material must be removed from the mating surfaces. If piercing is used, all holes need be inspected for radial cracking. Piercing Only piercing tools which produce-true and clean holes, equivalent to acceptable drilled holes should be used. When drilling through more than one sheet, hold the sheets securely together so there is no misalignment of holes due to shifting or separation of the sheets. Extreme pressure shall not be applied and holes shall not be punched through with the drill.Ĭ. All holes shall be drilled normal (at 90 degrees) to the working surface.ī. Drilling Rivet holes should be drilled in accordance with the following recommendationsĪ.
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