ASME B18.6.2:2020 pdf download

ASME B18.6.2:2020 pdf download.Square Head Set Screws and Slotted Headless Set Screws (Inch Series)
1 INTRODUCTION
1.1 Scope This Standard covers the complete general and dimen- sional data for square head and slotted headless set screws. Also included is Nonmandatory Appendix A covering the formulas on which dimensional data are based, and Nonmandatory Appendix B covering wrench openings forsquare head setscrews. Where ques- tions arise concerningacceptance ofaproduct, the dimen- sions in the tables shall supersede those recalculated by formula. 1.2 Comparison to ISO Standards There is no comparable ISO standard for the fasteners specified by this Standard. 1.3 Dimensions Unless otherwise specified, all dimensions are in inches and shall apply before coating. 1.4 Options Options,wherespecified,shallbeatthediscretionofthe manufacturerunless otherwise agreedupon bythe manu- facturer and the purchaser. 1.5 Terminology For definitions of terms relating to fasteners or to component features thereof used in this Standard, refer to ASME B18.12, Glossary of Terms for Mechanical Fasteners. slotted headless set screw: screw with threads extending overtheentirelengthwithapointdesignedtobearagainst a matingpartatone end and a slotfor drivingatthe oppo- site end. square headsetscrew: screwwith threads extendingclose to the headatone end andapointdesignedto bearagainst a matingpartatthe opposite end. The head has a rounded top surface and four flat sides with an underhead construction that may be flat, conical, or rounded into a relief in the screw shank.
2 GENERALDATAFORSQUAREHEADSETSCREWS
2.1 Heads 2.1.1 Head Height. The head height is measured, parallel to the axis of the screw, from the top of the head to the intersection of the side of the head with the undersurface. 2.1.2 Width Across Flats. The maximum width across flats shall not be exceeded. However, on milled-from-bar, nonferrous screws, the maximum limit may conform to commercial tolerances of the bar stock material. No transverse section through the head height shall be less than the specified minimum width across flats. 2.1.3 Head True Position. The axis ofthe head shall be located at true position within a tolerance zone having a diameter equal to 6% of the specified maximum width across flats of the head, relative to the axis of the screw shank, regardless of feature size. For referee purposes, the evaluation shall be made by holding the body in a collet or chuck one bolt diameter from under the head and rotating the part. With the indicator inlinewiththeaxisoftheboltorscrew,findandrecordthe lowestpointon each flatorthe highestpointon each lobe. The true position is one-halfofthe largestabsolute differ- encebetweenthehighandlowvalues foranyopposingset of flats or lobes. 2.2 Length 2.2.1 Measurement. The length of square head set screws shall be measured parallel to the axis of the screw from the intersection of the side of the head with the undersurface to the extreme point. 2.2.2 Length Tolerance. The length tolerance for square head setscrews shall be as shown in Table 2.2.2-1. 2.3 Threads 2.3.1 Thread Series and Class. The threads on square head set screws shall be Unified Inch coarse, fine, or 8- thread series, Class 2A, in accordance with ASME B1.1. For threads with additive finish, the size limits of Class 2A apply before coating, and the thread after coating is subject to acceptance using a basic Class 3A size GO thread gage and a Class 2A thread gage for either minimum material or NO GO. 2.3.2 Thread Gaging. Unless otherwise specified, dimensional acceptabilityofscrewthreads shall be deter- mined based on System 21, ASME B1.3.2.5 Points 2.5.1 Point Types. When unspecified, square head set screws shall be supplied with cup points. Cup points may beknurled(internallyorexternally) atthemanufacturer’s option. Specifications forcone, dog, half-dog, flat, and oval points are in Table 2.5.1-1. 2.5.2 PointAngles. The external pointangles specified shall apply only to the portions ofthe point that lie below the thread root diameter, as angles within the thread profile may vary due to manufacturing processes. 2.5.3 Dog Points. When the length ofusable (effective) thread is less than the basic screw diameter, dog points shall not be used. Half-dog points shall be used for such screw lengths.