1、I INCH-POUND IA-A-3179ASeptember 17,2002SUPERSEDINGA-A-3 179October 28, 1998COMMERCIAL ITEM DESCRIPTIONSQUARES, MACHINISTS COMBINATIONThe General Services Administration has authorized the use of this commercial item descriptionby all federal agencies.1. SCOPE. This commercial item description cover
2、s machinists combination center and miter headsquares.2. CLASSIFICATION. The machinsts combination square shall conform to the following types:Type 1: Blade graduation divisions of 8ths and 16ths of an inch on one side; the opposite sidegraduation divisions of 32nds and 64ths of an inch.a71 Type2: B
3、lade *aduationdivisionsof 32ndsmd64thsofminchononeside;theoppositesidegraduation divisions of 50ths and 100ths of an inch.EF4HIADLOCKMUl-Figure 1. Machinists Combination. . Beneficial comments, recommendations, additions, deletions, clarifications, etc. and any other datawhich may improve this docum
4、ent should be sent to: General Services Administration, Federale Supply Service, Hardware SuperStore(6FEE), 1500 E. BanrristerRdBldg. #6, Kmsas City,Missouri 64131.FSC 5210Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3. SALIENT CHARACTERISTICSA-A-
5、3 179A3.1 Components. The square shall consist of a graduated blade, a square and miter head with a blade- a71clamping device, a level glass, and a scriber. A cast iron center head and protractor head shall befurnished if specified. (Protractor heads are not available for the 6 inch square.)3.2 Mate
6、rials. The component parts shall be fabricated from a fine grained, seasoned gray iron castingof uniform quality with a durable dark colored, smooth, or ripple finish on surfaces that are notmachined or polished and free of detrimental defects. The blade shall be steel, properly hardened,tempered, a
7、nd bright polished. The scriber shall be hardened steel. If a center head is specified, it shallbe of cast iron. If a protractor head is specified, the body shall be of cast iron and of single(nonreversible) or double (reversible) type, as specified by the procuring agency. The dial of theprotractor
8、 head shall be of cast iron, bright ground, chrome-plated satin finish, or a stainless steel plate,which is permanently secured to the cast iron dial and accurately fitted inside a circular space in thebody. The level glasses shall be fabricated of substantial glass or plastic tubing properly. The l
9、iquid inthe glass level shall be either clear or amber colored (“Cats eye”), at the option of the manufacturer. Theliquid shall not discolor, cloud, or noticeably change in fluidity with age or at temperature as low as -20Fahrenheit F) and as high as 125F.3.3 W. The blade shall conform to the dimens
10、ions specified in Table 1, for length designated. Theblade shall have a full-length groove along the center of one side to provide engagement with theclamping device of each head. The ruling edges and face shall be straight and parallel to each other.The blade graduations shall be permanently etched
11、 and read in reverse dkections and the graduationsand figures shall have a finish, which will make it possible for each accurate reading.TABLE 1. Dimensions, Types 1 the opposite side of the blade shall have divisions of 32nds of an inch on oneedge and 64ths of an inch on the other edge.2Provided by
12、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A-A-3 179A3.4.2 Type 2: One side of the blade shall have divisions of 32nds of an inch on one edge and 64ths ofan inch on the other edge; the opposite side of the blade shall have divisions of 50ths of an inch on
13、oneedge and to 100ths of an inch on the other edge.3.5 Sauare and Miter Head. The square, miter, and horizontal surfaces, including their adjacent sidesurfaces, shall be accurately finished. There shall be a significant slot for insertion of the blade. Theclamping device shall have a substantial knu
14、rled thumbscrew or thumbnut suitable for rigidly clampingthe head of any point on the blade. The locking device shall be so designed to prevent slipping from thehead when the blade has been removed. The level glass to be parallel with the square face of the head,and the scriber shall be pointed, pro
15、vided with a knurled head, and be either mechanically or frictionallyheld in a brass bushed hole. in the head.3.6 Center Head. When specified, a center head shall be furnished. The inside area surfaces, includlngtheir adjacent side surface, shall be accurately finished straight, true and square. The
16、 arms shall includea 90 angle with a tolerance of*15 minutes with the vertex of the arms centering the edge of the blade.Either arm of the center head shall be at 1/2 the included angle *3 minutes with either edge of the blade,There shall be a significant slot for insertion of the blade and a substa
17、ntial knurled thumbscrew orthumbnut suitable for securel y holding the head at any point on the blade, The locking device shall beso designed to prevent slipping from the head when the blade has been removed. The arm length,measured along the inside surface, on 6 inch blade squares shall be 2 inches
18、 *1/8 inch. On squares with12 inch or longer blades, the arms shall be 2 3/8 inches +1/8 inch.3.7 Protractor Head. When specified, a protractor head shall be furnished. When used in conjunctionwith the graduated blade, it shall be suitable for use as a bevel protractor. The protractor head shrdlcons
19、ist of a body, a turret-type dial with level glass, and 2 or more clamping devices with substantialknurled thumbscrews or thumbnuts. The locking device shall be so designed to prevent slipping fromthe head when the blade has been removed. One clamping device shrdl be suitable for rigidly clampingthe
20、 protractor body to the blade and the other shall be suitable for rigidly clamping body to the dird.3.7.1 Protractor Body. The straight edges and finished portion of the protractor body shall be finishedstraight, true and square and shall be not less than 6 3/8 inches nor more than 7 1/4 inches long
21、. Thebody shall have 1 or more zero index lines, each marked with a figure zero. The single (non-reversible)type of body, as specified, shall have a single straight edge arranged to extend over one face of thegraduated blade and capable of complete rotation about the dial. The double (reversible) ty
22、pe of body,as specified, shall have 2 equal length straight edges, each extending equal distance over opposite facesof the graduated blade. One straight edge of the double (reversible) type body may be detachable, at theoption of the user.3.7.2 Dial. The dial shall be accurately fitted inside a circ
23、ular space in the body, The peripheral surfaceof the dial and the inside surface of the circular space of the body shall be accurately finished. The dialshall be graduated over an arc of 180, and graduations and figures shall be arranged to read from zeroto 90 in either direction at the zero index,
24、or from zero to 180 with two sets of figures reading inopposite directions. The angle graduations shall be subdivided to 10 and marked to show each 100. Thespirit level shall be permanently secured to the dial and arranged parallel to the straight edges of theblades. The graduations shall have durab
25、le tilling of black color.3.8 Level glasses. The level glasses shall have permanent and readily distinguishable black bubbledefining lines, suitable for properly centering the bubble. Level shall be permanently secured to the head3Provided by IHSNot for ResaleNo reproduction or networking permitted
26、without license from IHS-,-,-A-A-3 179A sand enclosed by a metal housing in a manner such that only the portion necessary for observing thebubble positions is exposed.3.9 Tolerances and Accuracy. a713.9.1 Blade Length Tolerance. The blade length tolerance for 6 inch blade shall be +0.004 to -0,002in
27、ches. The blade length tolerance for 12 inch blade shall be +0.005 to -0.010 inches. The blade lengthtolerance for 24 inch blade shall be +0.007 to -0.0 12inches.3.9.2 Scale Centering Error. The scale centering error shall be measured from the leading edge of thefirst 1/2 inch graduation to the zero
28、 blade end and from the leading edge of the last 1/2 inch graduationto the opposite blade end. The scale centering error shall not exceed iO.0025 inches for eachmeasurement.3.9.3 Scale Graduation Error The scale graduation error shall conform to the specifications in Table 2,Table 2. Scale Graduatio
29、n ErrorLength (In.) Measurement Error (In.)First 6 Between left scale end and any + 0.004 to -0.0035graduation6 X12 Between left scale end and any + 0.005 to -0.0035graduation12 XS18 Between the zero scale end and any + 0.006 to -0.0035graduation18 X24 Between the zero scale end and any + 0.007 to -
30、0.0035graduation3.9.4 Squareness of blade. Both blade ends shall be square to both blade edges within an angle of 90*5 minutes.3.9.5 Squareness. The out-of-square error of the head with either edge of the blade shall not exceed0.004 inch per foot of the extended blade when measured at the end of the
31、 blade. The out-of-squareerror of the blade face shall not exceed a total of 1/32 inch in 12 inches. For blade lengths in excess of12 inches, the 12-inch point shall be the point of measurement.3.9.6 Miter. The out-of-miter error of the head with either edge of the blade shall not exceed 0.004 inchp
32、er foot.3.9.7 Protractor. The error in any angular measurement on the scale with either graduated blade edgeand either straight edge of the protractor body shall not exceed 15 minutes.3.9.8 Center Head. The blade shall bisect the included angle, as measured, of the center head within atolerance of +
33、3 minutes. The level vial shall have a vial sensitivity not to exceed 50 minutes and shall beset in the square head parallel to the base tithir 0.012 inch per foot.4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1.# ,A-A-3 179A3.9.9 Standard Commerc
34、ial Tolerance, Unless otherwise specified, standard commercial tolerances shallapply to all dimensions.3.10 Marking. Mark each item in a permanent and legible manner with manufacturers part number,manufacturers name or identifying symbol. All markings shall be made directly on the items surface insu
35、ch a manner that it remains clearly legible throughout the life of the item.4. REGULATORY REQUIREMENTS.4.1 Recovered Materials. The offeror/contractor is encouraged to use recovered materials to themaximum extent practicable, in accordance with paragraph 23.403 of the Federal acquisition Regulation(
36、FAR).5. PRODUCT CONFORMANCE.5.1 Product Conformance. The products provided shall meet the salient characteristics of thisCommercial Item Description, conform to the producers own drawings, specifications, standards, andquality assurance practices and be the same product offered for sale in the comme
37、rcial market. TheGovernment reserves the right to require proof of such conformance.5.2 Resuonsibilitv for Inspection. Unless otherwise specified, the contractor is responsible for theperformance of all inspection requirements and may use any commercial facilities (including thecontractors own facil
38、ities) suitable for performance of the inspection requirements, unless disapprovedby the Government. The Government reserves the right to perform any of the inspections deemednecessary to assure the item conforms to the specified requirements.6. PACKAGING. Preservation, packaging and marking shall b
39、e as specified in the contractor order.7. NOTES. This section contains information of a general or explanatory nature that is not mandatory.7.1 Source of Documents.Federal Acquisition Regulation (FAR): Government Printing Office, Superintendent of Documents,Washington DC. 20401-9371.7.2 Ordering Dat
40、a. Purchasers should select the preferred options permitted herein and should includethe following information in procurement documents.a.b.c.d.e.f.Title, number: and date of Commercial Item Description.Type.Size.Center Head.Protractor Head.1. Single (Non-reversible)2. Double (Reversible)Packaging r
41、equirements.5Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-7.3 National Stock Numbers (N A-A-3 179A : SNS). The following is a list of NSNs assigned which correspond to this ; tCID. The list may not be indicative of all possible NSNS associated wit
42、h the CID,5210-00-224-99375210-00-450-69205210-00-540-35135210-00-078-89445210-00-078-89475210-00-078-89485210-00-078-8949521 O-OO-O78-895OMILITARY INTERESTS:None: DoD has no registered interestin revisions and amendments to thisCommercial Item Description untilfurther notice,TJp& Size1 G1 12 in.1 12 in.2 6 in,2 12 in.2 12 in.2 12 in.2 24 in.pREPARING ACTIVITY:GSA-FSSProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
