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, there is a list of the most frequent problems and the steps to do 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.

Why?

A new constraint may need to remove two degrees-of-freedom from the sketch, but the sketch has only one degree-of-freedom.

Example: Coincident-Constraint

If a Point* has a Coincident constraint with a Line.

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

You must delete the constraint between the Point* and the Line before you can add a constraint between the Point* and Point*.

1.SHIFT-CLICK the Point* so that the Point* and the Coincident constraint show in the Selection-Window

2.Right-click the Coincident constraint, and select Delete element in shortcut menu.

* Point, end-Point, start-Point, or center-Point.

If your sketch disappears:

1.Do CTRL + Z

Example problems:

•The sketch collapses to a small dot.

•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