|In this task, you are going to
attach sketcher elements together by using the Fix Together command. This
capability lets you constrain a set of geometric elements even if
constraints or dimensions are already defined for some of them. Once
constrained, the set is considered as rigid and can be easily moved just by
dragging one of its elements.
One of the interest of this capability is that it also allows you to make 2D kinematics studies in the Sketcher.
This task shows you how to make two elongated holes perpendicular, then how to position them inside a rectangle, while using the Fix Together command.
|Create a rectangle and two non-constrained elongated holes next to it.|
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.
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
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.
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.
The Fix together constraint is
created as indicated by a green paper clip symbol.
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.
Just to check that you can now manipulate each hole by keeping its rigid body.
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 pre-selection 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:
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 over-defined constraints (between Fixed Together geometric elements) and the part is successfully updated.
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.
You can copy and paste a fix together set (not the constraint alone). To do so:
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:
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.
The Fix Together
command is a way of getting better solving performances as well as solving
more complex systems including rigid sub-parts.