Getting Started Tutorials - MechDesigner > Tutorial 3: Add a Sketch-Loop to a Part

You will frequently need to correct a sketch (trouble-shoot) with the Part-Editor.

Below, we list the most frequent problems and the procedures to follow to resolve them.

Note: We use these terms for sketch-elements: Blue if it is not fully-defined, and Black if it is fully-defined.

Sometimes, a sketch-element is BLUE and you cannot add more constraints.

You might be able to drag a sketch-element that is BLUE, but when you come to add a new constraint, MechDesigner does not accept it.

In this case, a new constraint may need to reduce two degrees-of-freedom from the sketch, but the sketch has only one degree-of-freedom that remains.

Example: Coincident-Constraint

If the end-Point of a Line has a Coincident Constraint with a Line, X-axis or Y-axis.

Then: it is not possible to also add a new Coincident-Constraint between the Point and a different Point.

To delete the constraint:

1.SHIFT-CLICK the end-Point of the Circle so that the Point and the Coincident Constraint show in the Selection-Window

2.Delete the Coincident-Constraint using the Selection-Window

If your sketch disappears:

- or -

1.Do CTRL + Z

Example problems:

•The sketch collapses to a small dot.

•The start-Points, end-Points, or center-Point are not the ends of Lines or Arcs.

•The sketch explodes to the size of a planet.

The sketch-elements become BLACK when you believe they should be BLUE.

To correct this problem, do one of these actions:

- or -

1.Do CTRL + Z

If the sketch-elements remain BLACK, then the

To delete a constraint you must 'find the constraint':

1.SHIFT+CLICK the sketch-element in the Graphic-Area

2.Right-click the element in the Selection-Window

3.Delete a constraint or dimension

You may need to delete more than one constraint. When sketch-elements becomes BLUE, add a different constraint or the sketch-element again.

Step 3.7: Trouble-shoot Geometry