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.ĭesignation Ø Pitch Internal / External Lead Number of Starts Pitch Diameter Class Major/ Minor Diameter Class Thread Direction M8 8 1.25 Both 1.25 1 6H/6g 6H/6g Right hand M8 X 0.75 8 0.75 Both 0.75 1 6H/6g 6H/6g Right hand M8 X Ph2.25P0.75 8 0.75 Both 2.25 3 6H/6g 6H/6g Right hand M8 - 4g8e 8 1.25 External 1.25 1 4g 8e Right hand M8 X 0.75 - 5G 8 0.75 Internal 1.25 1 5G 5G Right hand M8 - RH 8 1.25 Both 0.75 1 6H/6g 6H/6g Right hand M8 Ph2.25P0.75 - 4g8e - LH 8 0.75 External 2.25 3 4g 8e Left hand.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.
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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. ISO 965-2 Limits Charts for the allowed range of pitch, major and minor diameters for classes 6H and 6g.
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* 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. ISO 965-1 Tolerances The main document for ISO Metric Threads: ISO 68 Basic Profile Defines the basic profile of the thread including Pitch, Pitch Diameter, Heights, etc.Ī drawing with the above thread parameters.įormulas for the above parameters. Several ISO standards define together the ISO metric thread system: ISO Standard Topic What’s Include? ISO 261 Possible Combinations Lists in a chart all the possible Diameter/ Pitch Combinations.ĭefines the Coase Pitch and Fine Pitch series.