ASME B18.2.9 pdf download Straightness Gage and Gaging for Bolts and Screws
1 SCOPE This Standard describes a gage and procedure for checking bolt or screw straightness at maximum mate- rial condition (MMC).
2 COMPARISON WITH ISO 4759-1:2000 This Standarduses anadjustable gage, instead ofplain sleeve gages like the example shown in ISO 4759-1 Annex C, Figure C.24. The adjustable gage avoids the necessity of a different gage for each diameter–length combination, and for each difference in the specified tolerances on diameter and/or straightness of the fas- tener.
3 REFERENCED STANDARDS For undated references, the most recent issues of the referenced standards apply.
ASME B18.12, Glossary of Terms for Mechanical Fas- teners ASME Y14.5M, Dimensioning and Tolerancing
Publisher: The American Society of Mechanical Engi- neers (ASME), Three Park Avenue, New York, NY 10016-5990;
Order Department: 22 Law Drive, P.O. Box 2300, Fairfield, NJ 07007 ISO 4759-1:2000 Tolerances for fasteners — Part 1: Bolts, Screws, Studs and Nuts — ProductGrades A, B, and C Publisher: International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, Case Postale 56, CH-1211 Gene`ve 20, Switzerland/Suisse 4 TERMINOLOGY For definitions of terms relating to fasteners or featuresthereofusedinthisStandard,referto ASME B18.12. 1 5 DIMENSIONS For definitions of terms relating to dimensioning and tolerancing, refer to ASME Y14.5M.
6 GAGE The gage consists of a stationary rail, an adjustable rail, micrometers that indicate the distance between the rails at each end, and a means to secure the adjustable rail in place. A typical gage is illustrated in Fig. 1.
(a) The excluded length, illustrated in Fig. 2, is the length, ifany, thatis to be excluded from the straightness gage, as specified by the product standard.
(b) The gaged length, illustrated in Fig. 2, is calculated as the bolt or screw length minus the excluded length.
(c) The straightness tolerance at MMC for the product to be inspected is calculated for the gaged length by the formula specified in the product standard.
(d) The resultant condition is calculated as the larger of the maximum major diameter of the thread or the maximum body diameter of the bolt or screw, plus the straightness tolerance at MMC.
(e) The adjustable rail of the gage is adjusted to pro- vide a parallel space between the rails equal to the resul- tant condition by obtaining common readings on both micrometer heads, and is secured in place.
(f) The gaged length of the product to be inspected is inserted between the rails, then rotated by hand through a full 360 deg. Any interference occurring between the product and the gage sufficient to prevent rotation indicates that the specified straightness is not met.