### GD&T Dialog Box - Feature Control Frame tab

GD&T dialog box - Feature Control Frame tab

The Feature Control Frame tab helps you construct a Feature Control Frame (FCF). It provides you with the tools to define datum features, select the features used in the FCF dimension, an editor to define the specific symbols, tolerances, and datums used in your FCF, and a preview area to see the current state of the FCF as you build it. For information on the various items in this tab, see the list of controls below:

ID - This box displays the name for the FCF. You can edit it if you want something different.

Features - This list lets you choose the considered features for a particular FCF type. Some features may exist in the part program, but are not available to the feature control frame. For example, a plane feature is not available to Circularity. PC-DMIS updates this list after you select the first feature. This ensures that when you create a pattern of features for the FCF, those features are compatible features.

Datums - The Datums shows all the datums defined with DATDEF commands. It only lists datum features above the current cursor position in the Edit window. Datums are always referenced in the FCF using the defined letters that represents those datums (for example, A, B and C).

Leader Lines - This list shows the same features that you selected from the Features list. Each feature has a check box associated with it. When you select a check box, PC-DMIS draws a leader line in the Graphics Display window from the FCF to that feature. By default, PC-DMIS initially displays all possible leader lines, but you can clear check boxes to turn off leader lines as well.

Feature Control Frame Editor - This area lets you apply changes to the FCF. You can select fields with the mouse or by pressing TAB and then ENTER to place the field into edit mode. If the field is editable, it will either display a drop-down list of available options, or it will display a box into which you can type text. When finished editing a field, press ENTER, TAB, or click on a different field to exit the edit mode. Pressing SHIFT + TAB will move backwards to the previous field.

When a field is empty a short description is displayed with brackets around it for identification. These descriptions correspond to these fields:

<UA> - Unit Area (only for Flatness FCF dimensions. See the "Per Unit check box" information below.)

<UZ> - Unequal tolerance zone (only for Profile FCF dimensions)

<UTol> - Unequal tolerance value (only for Profile FCF dimensions)

<MC> - Material condition

<size> - Material boundary size

<D> - Diameter

<Dim> - Dimension or feature control frame type

<PZ> - Projected zone

<num> - Number of features

<nom> - Nominal of feature size

<+tol> - Plus tolerance

<-tol> - Minus tolerance

<tol> - Tolerance

<dat> - Datum

<sym> - Dimension symbol

[x,y,z or u,v,w] - Customized datum reference frames. See "Creating a Customized Datum Reference Frame".

<add notes here> - Note field in the first line

<add optional design notes> - Optional design notes in the last line

Spherical Zone - You can use a spherical tolerance zone if you have a Position FCF for a point or sphere feature. To enable a spherical tolerance zone, select the feature to dimension, then in the FCF editor, select the diameter symbol and change it to the spherical zone symbol as shown here:

Planar Zone - This button appears in the Feature Control Frame Editor area of this tab if you are defining a Position FCF dimension or one of the orientation FCF dimensions (Perpendicularity, Parallelism, or Angularity) and the tolerance zone is set to a planar zone. To enable a planar zone and display this button, select the diameter symbol from the FCF editor and set it to blank as shown here:

Once the Planar Zone button appears, you can click it to open the Planar Zone Direction dialog box.

The Planar Zone Direction dialog box lets you specify the direction vector for the planar zone in one of two ways:

- Choose an axis in the current active alignment. Select the Axis option. Then from the Axis list, select an axis from the list: X, Y, Z, Radial Arc, or Right Angle to Radial.

  Radial Arc / Right Angle to Radial

  You can apply a positional tolerance in two directions to features located by polar coordinate dimensions relative to the specified datums. To do this, define two FCF dimensions and apply a different planar tolerance in each direction. One FCF dimension's tolerance should be a radial direction (Radial Arc). The other FCF dimension should be perpendicular to the imaginary center line that passes through the features (Right Angle to Radial). To evaluate the positional tolerance in these two directions simultaneously, you must create a SIMULTANEOUS EVALUATION command that references these two FCFs. See the "Simultaneously Evaluating Feature Control Frames" topic.

  Consider the following example. Suppose you have these two FCF dimensions applied to the circle labeled as item 1 in the diagram below:

  Dimension 1 using Radial Arc:

  Dimension 2 using Right Angle to Radial:

  Your Radial Arc tolerance (item 3) would then be a .04 wide tolerance zone applied to the arc that passes through the circle's centroid and the radius (R).

  Your Right Angle to Radial tolerance (item 2) would be a 0.2 wide tolerance zone parallel to the center line passing through center of datum D and circle 1.

  Diagram showing tolerance zones for Radial Arc (3) or Right Angle to Radial (2) applied to a circle (1)

- Input the IJK of the direction vector directly. Select the Vector option. Then in the I, J, and K boxes, type the direction vector.

This direction vector will be given in the current active alignment.

Datum Definitions - This button provides you with easy access to the Datum Definitions dialog box, allowing you to define datums for your current FCF dimension.

Feature Control Frame Options - The options in this area change based on the type of FCF dimension you are creating. These are discussed in detail below after this topic.

- Per Unit Check Box

- Form Only / Form and Location options

- Composite Check Box

- Axial and Radial Options

- Customized DRP Check Box

- GD&T Standard area

Actions and Procedures - This section displays hints and instructions to assist you in building valid FCFs.

Preview - This section displays a preview of the FCF with the current settings. It will not include any of the empty fields or empty descriptions that appear in the Feature Control Frame Editor section, for example fields that have brackets, such as
"<dat>".

Notes on the Feature Control Frame Editor

In the Feature Control Frame Editor area, be aware that some of the icon fields, if they are not supported, will not appear for certain dimensions. For example, if you have a Circularity dimension, PC-DMIS displays the tolerance field, but hides any datum or modifier fields.

Form dimensions (Circularity or Roundness, Cylindricity, Flatness, Profile with Form Only) - These don't support datums or modifiers, so these fields will not appear. Profile in some cases will fall in this category when checking for "Form Only". But "Form and Location" for Profile dimensions allows the display of modifiers.

Orientation dimensions (Parallelism, Perpendicularity, Angularity) - These allow datums and modifiers.

Location dimensions (Position, Concentricity, Coaxiality, Symmetry, Profile with Form and Location) - These allow datums and modifiers.

Runout dimensions - These must have datums.

Straightness dimension - This dimension supports modifiers if the feature being dimensioned for straightness is a cylinder feature. It does not support datums.

Also, only these dimensions can have multiple lines in the editor:

- Position

- Parallelism

- Perpendicularity

Tolerance Zones for Form Dimensions

For information on how PC-DMIS reports tolerance zones for form dimensions, see "Reported Tolerance Zones for Form Dimensions" in the "Reporting Measurement Results" chapter.