TR 60 x 18 (P9) LH would denoted two starts, as the lead divided by the pitch is two. If there is a suffix then the value after the multiplication sign is the lead and the value in the parentheses is the pitch. Precision steel pipes DIN EN 10305-1 to -5 dimensions and masses 28 30 Pipes with threaded ends DIN EN 10255 dimensions and masses 31 Steel pipes acc. When there is no suffix it is a single start thread. Where Tr designates a trapezoidal thread, 8 is the nominal diameter in millimeters, and 1.5 is the pitch in millimeters. Gages ISO metric trapezoidal screw thread are defined in the DIN 103-9. Trapezoidal threads are defined as follows by ISO standards: ISO 2901, ISO 2901, ISO 2903, ISO 2904 and ISO 103. Although metric screw threads are generally more prevalent worldwide than imperial threads, the Acme thread is very common worldwide, and may be more widely used than the trapezoidal metric thread. Trapezoidal threads are codified by DIN 103. The reason that the values for tolerance bands (signified by letters, found in table 1) are written as positive and negative numbers, and the values for tolerance classes (written as numbers, found in tables 2 - 5) are not, is because tolerance classes are applied interchangeably to both internal and external threads, and must be either subtracted or added to a tolerance, dependent on whether the thread is internal or external.External ISO Metric Trapezoidal Screw Threads Table Chart Sizes TR8 - TR315įastener and Screw / Bolt Design, Formula and Calculations For instance, a screw with a 6g major diameter tolerance and a 6g pitch diameter tolerance would simply be written as “6g”. Screws threads with identical external tolerances and pitch tolerances are expressed with a single tolerance letter and number. For more information on measuring pitch diameter, see our article on how to measure a screw.Īs an example, a common screw thread tolerance is 5g6g, which has a 5g tolerance on its pitch diameter, and a 6g tolerance on its external diameter. Din 931 indicates partially threaded hex head cap screw The DIN 931 standard will specify the thread tolerance. Screw threads are usually signified by two tolerances, one for the maximum outside diameter measure from the major diameter of the thread, and one for the pitch diameter, measured from the midpoint of each tooth. Grade 6 signifies general use, with smaller numbers being used for stricter tolerance, and higher numbers being used for more loose tolerances.įor instance, a 5G tolerance would signify a tolerance that is in the 5th tolerance class of band G. Tolerances are written as a combination of a tolerance band, signified by an alphabetic letter (E, G, e, f, g or h, with uppercase letters signifying internal threads, and lowercase signifying external), and a tolerance class, signified by a number. The information below can be used to calculate the values of thread tolerances defined by ISO 965/1.

Din thread specifications