Machinery's Handbook, 31st Edition
2016
Metric Screw Threads M Profile Table 4. American National Standard Minimum Rounded Root Radius— M Profile Series ANSI/ASME B1.13M-2005 (R2015)
Min. Root Radius, 0.125 P
Min. Root Radius, 0.125 P
Min. Root Radius, 0.125 P
Min. Root Radius, 0.125 P
Pitch P
Pitch P
Pitch P
Pitch P
0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.025 0.031 0.038 0.044 0.050 0.056 0.063
0.6 0.7
0.075 0.088 0.094 0.100 0.125 0.156
1.5 1.75
0.188 0.219 0.250 0.313 0.375 0.438
4
0.500 0.563 0.625 0.688 0.750 1.000
4.5
0.75 0.8
2
5
2.5
5.5
1
3
6 8
1.25
3.5
… … … … … …
All dimensions are in millimeters. Table 5. American National Standard Fine Pitch Metric Thread—M Profile Series ANSI/ASME B1.13M-2005 (R2015) Nom. Size Pitch Nom. Size Pitch Nom. Size Pitch Nom. Size Pitch 8 1 … 27 … 2 56 … 2 105 2 10 0.75 1.0 1.25 30 1.5 2 60 1.5 … 110 2 12 1 1.5 1.25 33 … 2 64 … 2 120 2 14 … 1.5 35 1.5 … 65 1.5 … 130 2 15 1 … 36 … 2 70 1.5 … 140 2 16 … 1.5 39 … 2 72 … 2 150 2 17 1 … 40 1.5 … 75 1.5 … 160 3 18 … 1.5 42 … 2 80 1.5 2 170 3 20 1 1.5 45 1.5 … 85 … 2 180 3 22 … 1.5 48 … 2 90 … 2 190 3 24 … 2 50 1.5 … 95 … 2 200 3 25 1.5 … 55 1.5 … 100 … 2 All dimensions are in millimeters. Limits and Fits for Metric Screw Threads—M Profile.— The International (ISO) metric tolerance system is based on a system of limits and fits. The limits of the tolerances on the mating parts together with their allowances (fundamental deviations) determine the fit of the assembly. For simplicity the system is described for cylindrical parts (see ISO Metric Limits and Fits starting on page 674) but in this Standard it is applied to screw threads. Holes are equivalent to internal threads and shafts to external threads. Basic Size: This is the zero line or surface at assembly where the interface of the two mat ing parts have a common reference. * Upper Deviation: This is the algebraic difference between the maximum limit of size and the basic size. It is designated by the French term “écart supérieur” ( ES for internal and es for external threads). Lower Deviation: This is the algebraic difference between the minimum limit of size and the basic size. It is designated by the French term “écart inférieur” ( EI for internal and ei for external threads). Fundamental Deviations (Allowances): These are the deviations which are closest to the basic size. In the accompanying figure they would be EI and es . * “Basic,” when used to identify a particular dimension in this Standard, such as basic major diameter, refers to the h/H tolerance position (zero fundamental deviation) value.
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