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Modifying GD&T and FTA in CATIA

Tips and TacticsModify GD&T and FTA in CATIA

There are some tricks to using FTA in CATIA and creating your GD&T that can make your modeling a lot easier. Read on to find out more.

 

FTA datum

When adding GD&T to a part in Catia, Catia's  application method often causes changes in appearance. The user may have to change the surface a datum is on, reconnect a prequalifier or alter the appearance of the GD&T itself in order to properly display their GD&T. 

Here are a few tips for changing and improving GD&T in Catia. 

FTA options in Catia

Setting Options

First thing's first. Make sure all of the Dimension Manipulators are active. These are the options that allow you to use all of the FTA and GD&T options within Catia. 

To turn all of these on, go to Tools -> Options. 

In the tree, select Mechanical Design and then select Functional Tolerancing and Annotation. Under the Manipulator's tab, add all the checks for Dimension Manipulator under Creation and Modify

You can also change the Manipulator's size by either increasing the reference size or turning off the "Zoomable" function. 

  • Zoomable - will make the symbol larger or smaller when zooming in or out.
  • Reference Size - determines the size of your GD&T. When Zoomable is on, the symbol will remain 2mm; when Zoomable is off, the symbol will remain the same size on your screen.

New Options

After turning on the Dimension Manipulators, options will be available to the user outside of Preferences. You can Right-click on the yellow options diamond to bring up an options menu. 

There are different options for each feature in Catia. Dimensions and text have similar options, while GD&T has a lot of other hidden options. 

FTA GD&T yellow diamond options

Options: Dimension Lines and Text

Overrun and Blanking

These two options are located at the top and bottom of a dimension (length dimension, etc.). To edit one, double-click on one of the squares and enter in a value or drag the squares up and down. You're going to want to see a picture for this.

FTA GD&T options dimensions

Text before and After

These are located before and after a dimension number. Select the arrows before or after the dimension to enter in text. 

Note: If using the Tolerance Advisor, text may already be inserted into the dimension (see 4x below for an example). 

FTA GD&T gdt modifications

Move Value FTA GD&T Move value

This will move the dimension value along the dimension line. Some dimensions may have two or more values. 

Move Dimension LineFTA GD&T move dimension

This option is located in the center of the dimension line. The dimension will also move by dragging the dimension line, but with the block in the center, the value will not snap to the mouse. 

FTA GD&T option values

Move Dimension LeaderFTA GD&T Move dimension leader

The dimension leader will only show if the user changes the dimenion line. To change the dimension line, select a dimension and then select the dimenison line option. 

FTA GD&T move dimension leader2

GD T set

Options: GD&T

It's time to change up some GD&T. Right click your GD&T and take a look at the options list. 

Here are some of the options you should see:

FTA GDAssociated Geometry: If the leader of the GD&T is pointed to a surface, the user can change the pointed geometry without destroying links made by the Tolerance Advisor.

Select Views: Select the view the GD&T (as well as Dimensions and text) is associated with. 

Transfer to View: After adding a new view plane, the user can change the GD&T to the new view plane. 

Add leader: Add a leader from the GD&T to either a surface, line or a dimension. It will also keep the GD&T parallel to the view plane and create a positional link to that dimension. 

Annotation Links: The user can remove a positional or orientation link along with other dimensions or datums. 

Connection Management

A dialog box will appear after selecting this option. To change the GD&T to a different surface:

  1. Right-click on the GD&T and select Associated Geometry
  2. Select one of the components to show which surface to change
  3. Right-click on the component surfaces and select Connect, the icon to the left will change
  4. Pick the new surface in the graphic window
  5. Pick the Check Validity button to verify that the change worked with that specific surface and their Datums. 
  6. Select OK. 
FTA GD&T connection management

Leaders

FTA GD&T gdt leader position
Leader Position: The leader position can be dragged through the FT&A. It can be moved to each corner and mid-point on each square. Right-click to set other options:
  • Automatic Mode: This will set the position of the leader to the corner.
  • Standard Behavior On/Off: With this on, the circle will only go to the mid-points of each end; with it off, the user will be able to set it to the end point and/or mid-point.

Other selections GDT and FTALeader Anchor:
After right-clicking on the Leader Anchor, this set of options comes up:
  • Breakpoint: Adding a breakpoint will break the leader by adding another segment. From there the user can create one or more leader lines.
  • Interruption: This will add a space to the leader, if, for example, it is crashing through another dimension line. 


GDT and FTA Leader ListMore Leaders

  • Remove Leader/Extremity: Removes a leader. If there are more extremities, it will still remove the whole leader. 
  • All Around: Add a circle to the corner of the leader. 
  • Perpendicular Leader: This makes the leader perpendicular to the surface or line. 
  • Dimensions of Visualizations: Will add a dimensions line to the FT&A. However, the dimesnion line will be separate from the FT&A and cannot be modified. 
  • Symbol: Change the shapes of the arrow at the end of the leader. 

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Topics: CATIA 3DCS T&T