TOP-TIP 1 - Complex Sketches in the Part-Editor.

The Part-Editor is not as powerful as those found in 3D CAD software. The Part-Editor is not meant to be a sketch editor for complex geometry.

Do not try to add a very complex sketch. Keep them basic.

Remember, MechDesigner is a design and analysis tool for kinematics - not a 3D Modelling tool.

TOP-TIP 2 - Construction vs Sketch-Loop Geometry.

Construction geometry:

Add each sketch-element as a 'free element', then use Constraints

TOP-TIP 3 - Large-Models

Large Models:

Toggle-out the Auto-Update tool.
Toggle-in the Auto-update occasionally, to make sure the model is up-to-date.
Toggle-in the Auto-Update before exporting data changes.

How to use the Part-Editor

Why edit a Part
How do I 'Start the Part-Editor'?
How many Parts can I edit at one time?
How do 'I know I am using the Part-Editor'?
Why does the Part-Outline go out of view when I start the Part-Editor?
Can I edit the Part-Outline?
How do I 'Edit the Length of a Part'?
Why is the dimension negative in the Dimension dialog?
How do I 'Add a Sketch-Loop'?
Why do I need to add Geometry to the Base-Part?.
What are the colour Codes used in the Part-Editor?
Why can I not delete a sketch-element.
Trouble-shooting in the sketch-editor.

Trouble-shooting the sketch-editor.

Where is my Sketch?


If your sketch changes in an unexpected way, and you cannot Drag to recover it:

Use Edit Menu > Undo, or CTRL + Z

To return the sketch to state it was in before:

Use Edit menu > Undo or CTRL + Z

Sometimes the Sketch 'Collapses' to a small dot.

Use Edit menu > Undo or CTRL + Z

Sometimes the Sketch 'Explodes to the size of a planet.

Use Edit menu > Undo or CTRL + Z

Why is my sketch BLACK when it should be BLUE?

Sometimes, a sketch-element is BLACK but you know it should be BLUE. You should be able to add a dimension or constraint to it, but you cannot.

Or, a sketch-element is BLUE  when it should be BLACK.

The best solution is to do one of these actions:

Delete the sketch-element to add it again.
Click the sketch-element so it shows in the Selection-Window
Right-click a constraint, or the sketch-element, and select 'Delete Element'.

- or -

Use Edit menu > Undo or CTRL + Z

Then add a different constraint.

You can add the same constraint again, or use a different constraint, to see if the sketch-element turns BLACK.

In our defence, the Part-Editor is continuously improved.

'Why is my sketch Blue, and I cannot add any more constraints?'

Sometimes, a sketch-element is BLUE but 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 remove two degrees-of-freedom, but the sketch has only one degree-of-freedom remaining.


Add Coincident Constraint between the centre-Point of a Circle and a Point at the end of a Line.

If: the centre-Point of the Circle has a Coincident Constraint with the Line,

Then: it is not possible to also add a Coincident-Constraint with a Point at the end of the Line

1.Click the centre-Point of the Circle so it shows in the Selection-Window
2.Delete the Coincident Constraint using the Selection-Window

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd