Making Elongated Holes Perpendicular
Prior to using the Fix Together command, consider the
following scenario: to make both elongated holes perpendicular to each
other, you could be tempted to select one oblong hole then drag it next to
the second one, and eventually set a perpendicular constraint. The fact is
that setting the constraint if no other constraints are set, deforms the
holes. To quickly achieve the desired geometry, follow the steps as
explained below.

Click Fix Together
.
From V5R17 onwards, as soon as Fix
Together is selected, the Fix Together Definition dialog
box is displayed even if no geometry is selected.

Select one elongated hole by using the selection trap.
The Fix Together Definition dialog
box that appears displays all selected geometrical elements.
Selecting Geometrical Elements
Dependencies
To assume that the rigid body behavior can be managed, by default the
application includes element dependencies. When adding a spline
for instance, all its control points and control point tangencies are
automatically added even if they were not selected.
The following table lists geometric elements and their corresponding
dependencies:

Geometric Element 
Dependency 

Line 
Start point + End point 

Circle/Ellipse 
Center point 

Arc of Circle/Ellipse 
Enter point + Start point + End point 

Parabola/Hyperbola 
Start point + End point 

Conic by two points 
Start point + End point + (Start Tangent
curve + End Tangent curve) or Tangent Intersection point +
(Passing point or Not) 

Conic by four points 
Four points + One Tangent curve 

Conic by five points 
Five points 

Connect Curve 
First point + Second point + First curve +
Second curve 

Spline 
Control points + Tangent directions 
Number of Elements
You can select as many geometrical elements as you wish, but just
remember that a geometrical element can be used by only one Fix Together
constraint.
Whenever
you wish to remove elements from the selection, just rightclick the
element of interest and select Delete. Alternatively,
just select the element in the geometry area again.
Absolute Axis
You can select the origin, the H or V Direction of the sketch absolute
axis. These three elements cannot be selected at the same time by a
selection trap. You need to explicitly select them one by one.

Click OK to confirm.
The Fix together constraint is
created as indicated by a green paper clip symbol.
Degrees of Freedom
The set of geometric elements constrained by Fix Together has
three degrees of freedom whatever the number of elements. In order to be
fully defined, the set needs to be dimensioned to fix geometry taking up at
least the three degrees of freedom (one rotation and two translations).
A geometric element included in a set of elements constrained via
Fix Together
can also be constrained using
.
If, for instance, a Fix Together constraint contains a fixed line, the set
of geometric elements has one single degree of freedom which is along the
direction of the line.

Repeat the operation for the second elongated hole.
Just to check that you can now manipulate each
hole by keeping its rigid body.

Select them and drag them to any location.

Set the perpendicular constraint.
Positioning Holes in the Rectangle

To position both holes inside the rectangle, delete the
constraints you previously set.

Create only one Fix Together for both holes.

Drag the holes all together inside the rectangle after
selecting any of their geometrical element and add constraints between
the rectangle and the holes to specify their exact positions.

Select the Fix Together constraint attaching
the holes and use the FixTogether.x object > Deactivate
contextual menu item. Note that if the Fix Together constraint is deactivated, the geometric
elements are always seen by the application as belonging to a rigid set.
So selecting them remains impossible for defining another Fix Together
constraint. You can now modify the shapes of the holes as the constraint is
deactivated.

Enlarge the right hole.

Note that passing the cursor over an activated or not Fix
Together constraint highlights the associated geometry.
Editing a Fix Together Constraint
You can add a geometrical element to a Fix Together
constraint provided it belongs to the current sketch and is not already
included in another Fix Together constraint. The selection or the
preselection of the elements to add depends on this verification during
the Fix Together constraint creation and editing.
You can add several elements at the same time either by using the CTRL
key or the selection trap. After a selection:
 Geometrical elements not used for the definition are added
 Geometrical elements that are already part of the definition are
removed.
Additional Constraints
 Adding constraints between elements involved in a Fix Together
constraint and other elements involved too in a distinct Fix Together
constraint or free elements allows you to position the fixed together
set.
 Adding a constraint to a fixed together element brings about an
overconstrained system. But unlike other types of constraints, when
exiting the Sketcher, the application does not detect no inconsistency.
 All existing or added constraints on geometric elements of a Fix
Together constraints are seen as overdefined (in purple when solving
status is displayed).
Except for Fix constraints, no constraints are solved between geometric
elements linked by the same Fix Together constraint. However, no update
error appears on such overdefined constraints (between Fixed Together
geometric elements) and the part is successfully updated.
Removing Geometrical Elements
You can remove geometrical elements from a Fix Together constraint by deleting the geometrical elements: dependencies are deleted too.
When the number of geometric elements in the set is less than two, the
Fix Together constraint is NOT automatically deleted.
Applying Operations Onto Fix Together Constraint
Copy/Paste
You can copy and paste a fix together set (not the constraint alone). To
do so:

Select the paper clip.

Use the Fix Together object > Select Geometrical
Elements contextual menu item.

Use Ctrl to include the paper clip in the selection.
or

Use the selection trap to ensure that the paper clip and
the associated constrained geometry are selected.

Apply the Copy > Paste capability.
Mirror
By switching off the Geometric constraints mode, the Fix
Together constraint is taken into account like the other constraints when
mirroring geometries and keeping the initial constraints:
...otherwise, the application
creates symmetry constraints as requested.
Break/Trim/Corner/Chamfer
You can apply the Break
,
Trim
,
Corner
and Chamfer
commands onto elements attached by a fix together constraint.
When all the geometrical elements belong to the same Fix Together
constraint, the constraint is updated accordingly. For instance,
when breaking a curve, the new half curve is automatically added to the
definition.
Methodology
Depending on your geometry and your needs, you will use the Fix
Together
command or the the Auto Constraint command, bearing in mind that:
 The Fix Together
command creates only one constraint for a group or elements.
 The Auto Constraint
command detects all possible constraints
between the selected elements then creates these constraints. This means
that sometimes you may create a lot of unnecessary constraints just for
imposing a rigid behavior. For more information, refer to Autoconstraining a Group of Elements in CATIA Sketcher User's Guide.
The Fix Together
command is a way of getting better solving performances as well as solving
more complex systems including rigid subparts.
