ASME B18.6.2:2020 pdf free download – Square Head Set Screws and Slotted Headless Set Screws(Inch Series)
1.1 Scope
This Standard covers the complete general and dimen-sional data for square head and slotted headless setscrews. Also included is Nonmandatory Appendix Acovering the formulas on which dimensional data arebased,and Nonmandatory Appendix B coveringwrench openings for square head set screws.Where ques-tions arise concerning acceptance of a product, the dimen-sions in the tables shall supersede those recalculated byformula.
1.2 Comparison to lso standards
There is no comparable lS0 standard for the fastenersspecified by this Standard.
1.3 Dimensions
Unless otherwise specified, all dimensions are in inchesand shall apply before coating.
1.4 Options
Options, where specified, shall be at the discretion of themanufacturer unless otherwise agreed upon by the manu-facturer and the purchaser.
1.5 Terminology
For definitions of terms relating to fasteners or tocomponent features thereof used in this Standard,refer to ASME B18.12,Glossary of Terms for MechanicalFasteners.
slotted headless set screw: screw with threads extendingover the entire length with a point designed to bear againsta mating part at one end and a slot for driving at the oppo-site end.
square head set screw: screw with threads extending closeto the head at one end and a point designed to bear againsta mating part at the opposite end.The head has a roundedtop surface and four flat sides with an underheadconstruction that may be flat, conical, or rounded intoa relief in the screw shank.
2.1.3 Head True Position.The axis of the head shall belocated at true position within a tolerance zone having adiameter equal to 6% of the specified maximum widthacross flats of the head, relative to the axis of thescrew shank,regardless of feature size. For refereepurposes, the evaluation shall be made by holding thebody in a collet or chuck one bolt diameter fromunder the head and rotating the part. With the indicatorin line with the axis of the bolt or screw, find and record thelowest point on each flat or the highest point on each lobe.The true position is one-half of the largest absolute differ-ence between the high and low values for any opposing setof flats or lobes.
2.2 Length
2.2.1 Measurement.The length of square head setscrews shall be measured parallel to the axis of thescrew from the intersection of the side of the headwith the undersurface to the extreme point.
2.2.2 Length Tolerance. The length tolerance forsquare head set screws shall be as shown in Table 2.2.2-1.2.3 Threads
2.3.1 Thread Series and Class.The threads on squarehead 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 Class2A apply before coating, and the thread after coating issubject to acceptance using a basic Class 3A size Gothread gage and a Class 2A thread gage for eitherminimum material or No Go.
2.3.2 Thread Gaging. Unless otherwise specified,dimensional acceptability of screw threads shall be deter-mined based on System 21,ASME B1.3.
2.4 Thread Length
Square head set screws shall have complete (full-form)threads extending over the portion of the screw lengththat is not affected by the point. For the respective constructions, threads shall extend into the neck relief,to the conical underside of the head,or within onethread (as measured with a thread ring gage) from theflat underside of the head.Threads through angular orcrowned portions of points shall have fully formedroots with partial crests. Because standard threadgages provide only for lengths of engagement up to11htimes the basic screw diameter, changes in pitchdiameter of either or both the external and internalthread may be required for applications involvinglonger lengths of engagement.