## Specifying Datum Features at LMC

Where a datum feature of size is specified on an LMC basis, a primary datum may be established as the axis or center plane of the LMC boundary. A secondary or tertiary datum may be established as the axis or center plane of the true geometric counterpart of the feature's virtual condition size. See para. 2.11 and Fig. 4-17. This example illustrates both secondary and tertiary datum features specified at LMC but simulated at virtual conditions. 4.5.6 Effects of Datum Precedence and Material...

## Positional Tolerancing For Symmetrical Relationships

Positional tolerancing for symmetrical relationships is that condition where the center plane of the actual mating envelope of one or more features is congruent with the axis or center plane of a datum feature within specified limits. MMC, LMC, or RFS modifiers may be specified to apply to both the tolerance and the datum feature. 5.13.1 Positional Tolerancing at MMC for As-ssmblability. A symmetrical relationship may be controlled by specifying a positional tolerance at MMC as in Fig. 5-59....

## Free State Variation

Free state variation is a term used to describe distortion of a part after removal of forces applied during manufacture. This distortion is principally due to weight and flexibility of the part and the relca.sc of internal stresses resulting from fabrication. A part of this kind, for example, a pan with a very thin wall in proportion to iLs diameter, is referred to as a nonrigid pan. In some cases, it may be required that the pan meet its tolerance requirements while in the free state. See Fig....

## Fig Profile Tolerancing Of A Conical Feature Datum Related

Ance is equal to the amount of such departure. See Figs. 6-41 and 6-42. 6.6.1.3 Tangent Plane. Where it is desired to control a feature surface established by the contacting points of that surface, the tangent plane symbol is added in the feature control frame after the stated tolerance. See Fig. 6-43. 6.6.2 Angularity. Angularity is the condition of a surface, center plane, or axis at a specified angle other than 90 from a datum plane or axis. 6.6.2.1 Angularity Tolerance. An angularity...

## Hole Pattern Dimensioning

00.25 feature-relatinfl tolerance zone cylinders 6 zones, basically related to each other and oriented to the datum 00.25 feature-relatinfl tolerance zone cylinders 6 zones, basically related to each other and oriented to the datum Actual feature axes must simultaneously lie within both tolerance zones -00.8 pattern-locating tolerance zone cylinders 6 zones, basically related to each other, basically located to the datums Actual feature axes must simultaneously lie within both tolerance zones...

## Fig Profile Of A Line And Size Control

Thecretical boundary shaped identically to the basic profile. For an internal feature, the boundary equals the MMC size of the profile minus the positional tolerance, and the entire feature surface must lie outside the boundary. For an external feature, the boundary equals the MMC size of the profile plus the positional tolerance, and the entire feature surface must lie within the boundary. To invoke this concept, the term BOUNDARY is placed beneath the positional tolerance feature control...

## Profile Control

A profile is the outline of an object in a given plane two-dimensional figure . Profiles are formed by projecting a three-dimensional figure onto a plane or by taking cross sections through the figure. The elements of a profile are straight lines, arcs, and other curved lines. If the drawing specifies individual tolerances for the elements or points of a profile, these elements or points must be individually verified. Such a procedure may be impracticable in certain cases, particularly where...

## Bidirectional Positional Tolerancing Of Features

Where it is desired to specify a greater tolerance in one direction than another, bidirectional positional tolerancing may be applied. Bidirectional positional tolerancing results in a noncylindrical tolerance zone for locating round holes therefore, the diameter symbol is omitted from the feature control frame in these applications. FIG. amp -36 NONPARALLEL HOLES INCLUDING THOSE NOT NORMAL TO SURFACE FIG. 5-37 SAME POSITIONAL TOLERANCE FOR HOLES AND COUNTERBORES, SAME DATUM REFERENCES FIG....

## Fig Different Positional Tolerance At Each End Of Long Hole

NOTE A further refinement of perpendicularity within the positional tolerance may be required. NOTE A further refinement of perpendicularity within the positional tolerance may be required. 5.9.1 Rectangular Coordinate Method. For holes located by rectangular coordinate dimensions, separate feature control frames are used to indicate the direction and magnitude of each positional tolerance relative to specified datums. See Fig. 5-41. The feature control frames are attached to dimension lines...

## May Be Applied As A Means Of Preventing An Abrupt Surface Variation Within A Relatively Short Length Of The Feature

0.1 diameter tolerance zone in each 25 mm of length The derived median line of the feature's actual local size must lie within a cylindrical tolerance zone of 0.4 diameter for the total 100 mm of length and within a 0.1 cylindrical tolerance zone for any 25 mm length, regardless of feature size. Each circular element of the surface must be within the specified limits of size. The derived median line of the feature's actual local size must lie within a cylindrical tolerance zone of 0.4 diameter...

## Runout

Runout is a composite tolcrance used to control the functional relationship of one or more features of a pan to a datum axis. 6.7.1 Runout Tolerance. The types of features controlled by runout tolerances include those surfaces constructed around a datum axis and those constructed at right angles to a datum axis. See Fig. 6-46. 6.7.1.1 Basis of Control. The datum axis is established by a diameter of sufficient length, two diameters having sufficient axial separation, or a diameter and a face at...

## Calculating Positional Tolerance

Figure 5-9 shows a drawing for one of two identical plates to be assembled with four 14 mm maximum diameter fasteners. The 14.25 minimum diameter clearance holes are selected with a size tolerance as shown. Using conventional positional tolerancing, the required tolerance is found by the equation as given in para. B3 of Appendix B. T H - F 14.25 - 14 0.25 diameter Cylindrical tolerance zone equal to positional tolerance Axis of hole at true position Axis of hole Is Axis of hole Is located Axis...

## Specifying Datum Features at MMC

Where a datum feature of size is applied on an MMC basis, machine and gaging elements in the processing equipment that remain constant in size may be used to simulate a true geometric counterpart of the feature and to establish the datum. In each case, the size of the true geometric counterpart is determined by the specified MMC limit of size of the datum feature, or its MMC virtual condition, where applicable. 4.5.4.1 Size of a Primary or Single Datum Feature. Where a primary or single datum...

## Fig Symmetrical Outlines

Round holes are dimensioned as shown in Fig. 1-34. Where it is not clear that a hole goes through, the abbreviation THRU follows a dimension. The depth dimension of a blind hole is the depth of the full diameter from the outer surface of the part. Where the depth dimension is not clear, as from a curved surface, the depth should be dimensioned. For methods of specifying blind holes, see Fig. 1-34. 1.8.10 Slotted Holes. Slotted holes are dimensioned as shown in Fig. 1-35. The...

## Projected Tolerance Zone

The application of this concept is recommended where the variation in perpendicularity of threaded or press-fit holes could cause fasteners, such as screws, studs, or pins, to interfere with mating parts. See Fig. 5-31. An interference can occur where a tolerance is specified for the location of a threaded or press-fit hole, and the hole is inclined within the positional limits. Unlike the floating fastener application involving clearance holes only, the attitude of a fixed fastener is governed...

## Fig Radial Hole Pattern Located By Composite Positional Tolerancing

FIG. 6-24 RADIAL HOLE PATTERN LOCATED BY COMPOSITE POSITIONAL TOLERANCING CONT'D Tolerance Zones for Radial Hole Pattern FIG. 6-24 RADIAL HOLE PATTERN LOCATED BY COMPOSITE POSITIONAL TOLERANCING CONT'D Tolerance Zones for Radial Hole Pattern 4X 00.6 pattern-locating tolerance zone cylinders at MMC. Pattern-locating tolerance zone framework PLTZF la located and oriented relative to datum plane A and datum axis B no rotational requirements r 4X 00.25 feature-relating tolerance zone cylinders at...

## First Part Of

CALLOUT MEANS THIS Datum plane A Pattern-locating tolerance zone framework PLTZF . 01 tolerance cylinders basically located and oriented relative to each other and to the specified datum reference frame. FIG. 5-22 COMPOSITE POSITIONAL TOLERANCING OF A CIRCULAR PATTERN OF FEATURES CONTD ADDITIONALLY, SECOND PART OF CALLOUT MEANS THIS One possible location and orientation of feature-relating tolerance zone framework FRTZF relative to pattern-locating tolerance zone framework PLTZF . FIG. amp -22...

## Datum Targets

Datum targets designate specific points, lines, or areas of contact on a part that are used in establishing a datum reference frame. Because of inherent irregularities, the entire surface of some features cannot be effectively used to establish a datum. Examples are nonplanar or uneven surfaces produced by casting, forging, or molding surfaces of weldments and thin-section surfaces subject to bowing, warping, or other inherent or induced distortions. Datum targets and datum features as...

## Asme 14.5.2 -2000

FThto Foreword is not a part of ASME Y14.5M-1994. Additions, modifications, and clarification contained in this revision of ANSI Y14.5M-1982 are intended to improve national and international standardization and to harmonize the United States practices and methodology with the universal standards trend toward more efficient worldwide technical communication. Coordinating and integrating these techniques into and via computer graphics and other electronic data systems for design, manufacture,...

## Circular and Cylindrical Targets

Circular target lines and cylindrical target areas may be used to establish a datum axis on rotating parts. See Fig. 4-36. 4.6.5 Secondary Datum Axis. For a secondary datum feature RFS , a set of thicc equally spaccd targets may be used to establish a datum axis. See Fig. 4-37. The centering device used to establish the datum axis has a set of three equally spaced contacting features capable of moving radially at an equal rate from a common axis that is perpendicular to the primary datum plane....

## Fig Repetitive Features

Where polar coordinate dimensioning is used to locate features, a linear and an angular dimension specifies a distance from a fixed point at an angular direction from two or three mutually perpendicular planes. The fixed point is the intersection of these planes. See Fig 1-51. 1.9.5 Repetitive Features or Dimensions. Repetitive features or dimensions may be specified by the use of an X in conjunction with a numeral to indicate the number of places required....

## Ansi B92.2m-1980

When the following American National Standards referred to in this Standard arc superseded by a revision approved by the American National Standards Institute, Inc., the revision shall apply. American National Standards ANSI B4.2-1978, Preferred Metric Limits and Fits ANSI B5.10-1981, Machine Tapers Self Holding and Steep Taper Series ANSI ASME B46.1-1985, Surface Texture Surface Roughness, Waviness, and Lay ANSI B89.3.1-1972, Measurement of Out-of-Roundness ANSI B92.1-1970,1 Involute Splines...