1.12: Tolerance Categories
Form Tolerances: control the SHAPE of features, are often used as a refinement of size.
Orientation Tolerances: Control TILT of features and are always associated with BASIC andle dimensions, used as a refinement to location. If applied to surfaces, orientation tolerances ALSO control FORM.
Location Tolerances: Control LOCATION, are always associated with BASIC liner dimensions. Position locates and orients the median plane or axis of FEATURES of SIZE. Profile locates feature surfaces. Profile is the most powerful characteristic of all, and also controls orientation and form.
1.17: Eng Drawing with GDT based upon functional requirements
the establishment of the DRF is based on the functional design of the part. see pictures Select Primary, secondary, and tertiary datum features accordingly.
Each dimension shall have a tolerance, unless specifically identified as reference, max, or stock (commercial stock size). Tolerance may be applied directly to dimension (indirectly in the case of basic dim.) or indicated by a general note in the title block.
Dim and tol shall be completele so there is full understancing of characteristics of each feature.
3.Dimensions and tolerances shall be selected and arranged to suit function and mating relationship of partand shall not be subject to more than one interpretation. Each neccessary dimension of an end project shall be shown in true profile views and refer to visible outlines. No more dimensions than those necessary for complete definition shall be given. Use of reference dimensions should be minimized.
Drawing should specify a part w/o specifying manufacturing methods. in instances where manufacturing, processing, quality assurance, or enviormental info is essential to definition of engineering requirements, it shall be specified on the drawing or in document referenced to drawing.
90degree angle w/ tol applies where center lines and lines depicting features are shown on a 2D orthographic drawing when defined by directly toleranced dimensions at right angles and no angle is spedified.
6.90degree basic angleapplies where centerline of features or surfaces shown at right angle on a 2D orthographic drawing when defined by basic dimensions and no angle is specified.
- A zero basic dimension applies where axes, center places, or surfaces are shown coincident on a drawing, and geotol establishes the relationship among the features.
8.Unless otherwise specified, all dimensions and tol are applicable at 20degreesC (68F) according to ANSI/ASME B89.6.2
9.unless otherwise specified, all dims and tols apply in free state condition
- unless otherwise specified, all tols apply for full depth length and width of feature
11.dims and tols apply only at the drawing level where specified. A dim specified for a given feature on one level of drawings(ex. detail drawings) is not mandatory for that feature at any other level (ex. assembly drawing)
- Where coordinate system is shown on the drawing, it shall be right handed unless otherwise specified. each axis shall be labeled and positive direction shall be shown.
2.3: Taylor Principle (Rule#1, Envelop/Taylor Principle)
The limits of size (rule#1) defines the size and form limits for regular, individual features. It requires perfect form at MMC and ensures the pin will fit in the hole. The limits of size define the size as well as the form of the individual feature. The form of the feature may vary within the size limits. If the feature is produced at MMC, the form must be perfect. The feature may be bent, tapered, or out of round as it departs from MMC.
Exception to rule#1- control of geometric form prescribed by the limits of size does not apply to the following: stock such as bars, sheets, tubing, structural shapes, and other items produced to established industry or government standards that prescribe limits for straightness flatness and other geometric characteristics.
2.8: Size does not control interrelationship between individual features.
3.2: +/- tolerancing to locate surface not clear
3.6: GDT Tol applied to a hole
3.10: Effect of MMC and LMC on a hole
4.3: Position Verification paper gage
4.7, 4.8 Position-- Rectangular to Diameter conversion chart
6.13: Datum Ref Frames and Simulators
The Datum Reference Frame consists of 3 mutually perpendicular datum planes and 3 mutually perpendicular datum axes that occur at the intersection of the datum planes and a datum point that occurs at the intersection of the three axes.
Datums are established from these datum feature simulators. See picture for datum feature simulator requirements.
Theoretical datum feature simulators are the perfect inverse of a datum feature.
Physical datum feature simulators are tooling and inspection equipment such as a collet, surface plate, gage block etc.
6.33: Datum- Constrained Degrees of Freedom
The datum features constrain the six degrees of freedom on a part. see pictures for constraints of translations and rotations.
7.10: Calculating Boundaries for Datum Features @ MMB
8.6: Datum Target Definition
11.2: Orientation Tolerances
13.2: Position Tolerances