ASME B1.13M:2005 pdf free download.Metric Screw Threads: M Profile.
5.4 Allowance/Tolerance Formulas and Tables
(a) See section 6 for pitch and crest diameter allowance/tolerance formulas and tables.
(b) Functional diameter size includes the effects of all variations in pitch diameter, thread form, and profile. The variations in the individual thread characteristics such as flank angle, lead, taper, and roundness on a given thread, cause the measurements of the pitch diameter and functional diameter to vary 1mm one another on most threads. The pitch diameter and functional diameter on a given thread are equal to one another only when the thread form is perfect. When required to inspect either the pitch diameter, the functional diameter, or both, for thread acceptance (see ASMF 131.3), use the same limits of size for the appropriate thread size and class.
5.5 Selected Tolerance Classes
5.3.1 External Thread Tolerance Classes. Small allowance (fundamental deviation)
(a) for normal tolerance — tolerance class hg6g
(b) for tighter tolerance — tolerance class 4g6g
(c) for a no-allowance fit at maximum material, such as for a plated bgbg — tolerance class 6hoh
5.5.2 Internal Thread Tolerance Class. No allowance (fundamental deviation). Tolerance class 611611. Internal threads with allowance are not standard practice.
5.6 Length ol Thread Engagement
5.6.1 Normal Length oITh read Engagement. The pitch diameter tolerances specified herein are applicable to the limits oF the normal length ol thread engagement LE in Table 7. The limits were calculated by formulas given in para. 6.4.
5.6.2 Short and Long Lengths of Thread Engagement When Gaged With Normal Length Contacts. For short LE length of thread engagement, reduce the pitch diameter tolerance of the external thread by one tolerance grade number. For long LE length of thread engagement, increase the allowance (fundamental deviation) at the pitch diameter of the external thread. For internal threads with long LE length of thread engagement, pro-
vide an allowance (fundamental deviation) correspond-ing to the next larger tolerance position. Thus,for thestandard H position (no allowance), a tolerance position
G would be provided. For assemblies with short or longlengths of engagement, the tolerance class adjustmentmay be applied to only one member. See Table 8.
5.7 Circular Runout
Circular runout is the full indicator movement (rotr(see ASME Y14.5). Runout of the crest (minor diameter of internal thread or major diameter of external thread)relative to the pitch cylinder shall not be so great thatthe basic profile is transgressed.
5.7.1 Internal Thread. When measurement is speci-fied, the runout of the minor diameter cylinder relativeto the pitch cylinder on the internal thread shall not exceed the difference between the measured minordiameter and the basic minor diameter. An out-of-roundpitch cylinder may reduce the available runout.
5.7.2 External Thread. When measurement is speci-fied, the runout of the major diameter cylinder relativeto the pitch cylinder on the external thread shall not exceed the difference between the measured major diam-eter and the basic major diameter.An out-of-round pitchcylinder may reduce the available runout.
ASME B1.13M:2005 pdf free download
