You can use 3D Grips to edit features on your models, but how does this affect existing constraints on your sketches?

3D Grips can move a sketch profile away from the origin of the sketch if it is not constrained.
In this short exercise you’ll see how constraining a node on the profile to the origin of the sketch prevents the profile from moving relative to the sketch origin.

First use the Standard Part template to create a 1-inch cube. Draw a square on the origin of the sketch plane, and constrain the node on the origin with a Fixed constraint or use the green snap dot to constrain the node. Add 1-inch dimensions for the height and width, and then extrude the square 1-inch.



How to use 3D Grips
The next step is to use 3D Grips to edit the cube. Before you get started, make the sketch visible so that you can see which corner of the sketch is constrained to the origin.

Now follow these steps.

1. Click any surface to highlight the surface.
2. Right click and select 3D Grips.
3. Place your pointer over a grip (the circles on the edges and faces of the cube) to display a grip arrow.
   
4. Drag the grip arrow to a new location.
5. Right click and select Done.

You can practice dragging grips to change the size and shape of the cube, and while you do, make the following observations.

• The grip arrows adjacent to the fixed sides of the sketch profile do not change the size of the sketch.
• The grips on the edge of the cube can be used to drag the geometry along two axes at the same time.

Before you finish practicing, be sure to try to adjust the cube by dragging an edge or face that is adjacent to the fixed node on the sketch profile. The edge that cannot be adjusted is the edge that is formed by the extrusion. It is perpendicular to the sketch profile, and one end of it is on the Fixed node.

Why is this example important?

This is a very good example of why you need to fully constrain all of your sketches. If the node on the corner of the sketch profile was not constrained to the origin of the sketch you can drag the edge away from the origin. If this was a more complicated part, the effect of doing this may not be obvious, and you would not know that the profile is no longer on the origin.. So an under-constrained sketch may change without you knowing it.

As a rule, I always suggest that you fully constrain all your sketches, and locate them on projected geometry.