E_B1_technical_report_1983.pdf

ASME B1*TECH*REPT930759b700532181380ASME B1 TECHNICAL REPORTMeasurement Uncertaintyfor 60 deg.Screw ThreadGage Element Measurement(Inch and Metric)习】The American Society ofMechanical Engineers345 East 47th Street,New York,N.Y.10017ASME B1*TECH*REPT930759b700532183T53FOREWORD(This Foreword is not part of the B1 Technical Report.)Every measurement has a degree of uncertainty.This problem surfaces when screw threadshad to assemble and be interchangable.Early standards writers provided safeguards by estab-lishing a common basic size where the products limits were not permitted to cross.All formsvariations which result in a functional size had to meet this requirement.As time progressed screw thread writers simplified the concept by placing Class 3 maxi-mum-material pitch diameter of both product and gage for internal and external threads atbasic,assuming both gage and product have no form variations.By doing this,it became difficultto manufacture gages with close tolerances to gage marginal product with certainty.This Report does not solve the screw thread standards concept.It recognizes that gages shallbe made to specified tolerances by the gagemaker,but may be outside the tolerance by a secondpartys uncertainty.At the October 1987 meeting of the ASME BI Committee in New York City,a workinggroup was created to address uncertainty.After several meetings,a scope and tentative measurement uncertainty values were proposed at the April 1989 meeting in Orlando,Florida.This Report represents the best estimates for measurement uncertainty for gage sizes through12 inches(300 millimeters).A gage is acceptable when a second partys measurement exceedsthe tolerance by the tabulated value.The uncertainty value may be changed at a future date if statistical data justify such a change.Suggestions for the improvement of this Report will be welcome.They should be sent toSecretary,ASME B1 Main Committee,345 East 47th Street,New York,NY 10017.This Technical Report was approved by the ASME Board on Standardization on October 19,1992.心