ASME B1.10M pdf download UNIFIED MINIATURE SIREW THREADS
This Standard specifies the thread form, series, tolerance, and designation for the Unified Miniature ScrewThreads. The series covers a diameter range of 0.30 mmto 1.40 mm, extending the metric M-Profile and unifiedthread series that begin at 1.6 mm.
1.2 Unified Miniature Screw Thread Standards
The fourteen sizes published in this Standard wereendorsed by the American-British-Canadian conferenceof April 1955 as the basis of the unified standard amonginch-using countries, and to correspond with the rangeof sizes in the ISO. The sizes are shown in Table 1. Ininterest of standardization and where design permitsselection of size should be confined to those indicatedin bold type in Table 1. For more restrictive conditions,those sizes indicated in regular type in Table 1 maybe used.
Unified Miniature Thread sizes of this series shall bedesignated on engineering drawings,in specificationsand on tools and gages (space permitting) by their nominal diameter in hundredths of a millimeter followed bythe symbol“UNM”(e.g, 0.80 UNM).On internal threads, the full limits of minor diameteras given in Table 2, shall normally be considered applicable. Where this is not permissible the designation shallbe supplemented by the minor diameter limits.
1.4 Reference Documents!
The following is a list of publications referenced inthis Standard
ASME B17,Nomenclature, Definitions, and Letter Symbols for Screw ThreadsASME B130MScrew ThreadsStandard Practice forCalculating and Rounding DimensionsPublisher: The American Society of Mechanical Engineers(ASME International),Three Park Avenue NewYork, NY 10016-5990; Order Department: 22 LawDrive, Box 2300,Fairfield,N 07007-2300
Additional recommended methods for determiningthe acceptability of miniature screw threads will beincluded as further experience with this thread standardis reported. Until such time, agreements must be reachedbetween purchaser and vendor regarding the basis fordetermining acceptance, since practices are likely to dif-fer considerably, particularly for external threads. Wherea free choice is possible, the procedures given below,which are being used with considerable success by someproducers, are suggested.
1.5.1 External Threads, The major diameter of theexternal thread is measured by either contact gagingoptical projection, or laser inspection equipment. Allother dimensions, such as pitch diameter, lead, threadform, and minor diameter may be inspected by opticalprojection methods, with a magnification of 100X recom-mended. A suggested chart for this method is shownin Appendix A. The thread plug gages and the tap areinspected in a similar manner to externally threadedparts. Contact gaging, such as the use of “GO” and”NOT GOring gages, measuring wires, and set pluggages may be used for sizes 0.70 UNM and above.
1.5.2 internal Threads. The minor diameter of theinternal thread is gaged with “GO” and“NOT GOplain cylindrical plug gages. All other elements arechecked only for assemble-ability limits by means of a“GO”thread plug gage, taking extreme care not to damage the thread. For the minimum material limits of theinternal threads, the accuracy and performance of thetap is relied upon. This implies that the major and pitchdiameters of the tap do not exceed the maximum inter-nal thread limits for these elements, and disregards overcutting, which is rarely incurred because of the flexibilityof these small taps and the manner in which they aregenerally fluted.
It is recommended that the minor diameter of theinternal thread be gaged with one insertion of the “NOTGO” plain cylindrical plug gage first. The“NOT GO”