In the next step, Step 1.4, we will make a PinJoint between a Point in the 'AddedPart' [Step 1.2] and a Point in the BasePart. The BasePart does not have a CADLine, or any other geometry. Thus, we must add geometry to it. Before we can make a PinJoint between the BasePart and the AddedPart, we must add a Point to the BasePart. However, we will add a Line to the BasePart. Note: Each AddedPart has a CADLine along its centre. Each Line and CADLine has a Point at its startPoint and a Point at its endPoint. 
➢  Learn how to start and close the PartEditor. 
➢  Learn how to add and delete geometric elements: sketchelements, dimensions and constraints in the PartEditor. 
➢  Learn why some dimensions are negative [it is a 'MechDesigner Rule']. 
➢  Learn that Black sketchelements are fullydefined, and Blue sketchelements are not fullydefined. 
1.  Start the PartEditor to edit the BasePart. 
2.  Add a Line sketchelement to the BasePart . 
3.  Add Dimensions and Constraints to define the Line in the BasePart. 
4.  Optionally, delete a Constraint, and add it again. 
5.  Close the PartEditor to return to the MechanismEditor. 
Tutorial 1: STEP 1.3 Add Line to BasePart 
To edit the BasePart:
There are many different ways to start the PartEditor. See also: How to Start the PartEditor 

Use the PartEditor to add, edit or delete 'Part Geometry. Part Geometry includes: sketchelements, and the constraints and dimensions that you add to and between sketchelements. When the PartEditor is active:

Now, add a Line to the BasePart:


Your pointer changes to the Add Line pointer.
The Drag technique for Add Line is identical to that for Add Part Note: Drag technique : 'Mousebutton down...move your mousepointer...mousebutton up': A Line shows in the PartEditor 


Expand the SketchConstraints toolbar to the RIGHT of the graphicarea.
[Notice your cursor changing to the Add CoincidentConstraint] Click two elements to add a Coincident Constraint. In this case we will do Add Coincident Constraint two times: we will select the Xaxis and a Point; and then the Yaxis and a Point. 

The Point 'snaps' to the Xaxis. Optional: If you deselect the Add CoincidentConstraint , you can still drag the Point along the Xaxis:


Optionally Drag the Point along the Xaxis 

If necessary, click AddCoincident Constraint again... We will now constraint the other Point to be on the Yaxis
The Point 'snaps' to the Yaxis. 

Again, if you deselect the Add Coincident Constraint icon, you can drag the Point along the Yaxis. 
If you have problems when you want to add a Constraint? The reasons is often:
Examples: Example 1: If you click the first element so that it becomes RED, and then click, but actually fail to click the second element... ...the first element 'deselects'. You must select the two elements again! Example 2: If you click, but miss, the first element, and then click the second element and it becomes RED You must click the first element again. Example 3: You accidentally click the Point AND the Line as the 'first' element, and then click the axis. The whole Line becomes collinear with the axis. You must delete the Coincident Constraint and then add it between the Point and the axis again. 
Constraints are not visible in the graphic area. To delete a constraint:
The constraint should now be in the SelectionWindow. 


Expand the Geometry toolbar to the LEFT of the graphicarea.


The dimension shows next to your pointer.


The Edit Dimension dialogbox opens immediately
Note: see How to edit a parameter in a dialogbox Edit the Dimension to be 50.00mm Note: To edit the Precision and Decimal Places for dimensions in the Application Settings dialogbox  NumberFormat > Precision / Digits 

Use Add Dimension again to add a dimension to the other Point.
The dimension shows next to your pointer.


See below: 'Why is the dimension negative?' Enter 120mm In the Dimension dialogbox But 120mm in the sketch. The Line becomes CYAN. This shows that the Line is 'fullyconstrained'. Now, you cannot drag the Line with your pointer. 
Dimensions of a Point relative to a Line or the Part's X or Yaxis. New convention in MechDesigner Release 10+: All Lines and Axes have their own Coordinate System (Origin and +X,+Y) . That is, Lines have an origin [its startPoint] and a +Xaxis direction [from its startPoint to its endPoint], with the +Yaxis direction at +90º to the +Xaxis. This is important when we dimension a Point relative to a Line because the dimension can be negative or positive. It might be most confusing when we click the Yaxis of a Part as a reference line. 

When we click the Yaxis as a reference Line:
When we add the dimension of the Point on the Xaxis, and click the Yaxis as a reference Line, the dimension will be negative with respect to the Coordinate System and axes of the Yaxis. Therefore, when we dimension the Point along the Xaxis, the dimension dialogbox shows –40.00. In the image, when we click the Yaxis as a reference Line to a dimension a Point, then Points in the area with the 'patch' will be negative in the Coordinate System of the Yaxis. 
You may need to edit the dimensions with the Dimension dialogbox. You cannot edit an element in the PartEditor when a different command is active.
You must deselect Add Dimension, because you cannot edit a dimension when a command is active. 

OR, click the dimension arrowhead one time, then edit from the SelectionWindow. The Dimension dialogbox opens. 

The 'Zero / Round' contextualmenu shows next to your pointer. Select 'Round' so the value changes to the nearest integer number that is exactly divisible by the spinbox increment value.
Do steps 25 again for the other dimension. Change the dimension that is between the Point on the Yaxis to the Xaxis to 50mm 
PartEditor icon 
Close the PartEditor: Do one of these procedures: In the graphicarea:
 or  In the graphicarea:
 or  In the graphicarea:
 or  To the left of the graphicarea: Deselect the Edit Part icon


Note: the Line in the BasePart is Green. In the PartEditor, the colour of each sketchelement in a Part is Blue or CYAN to indicate if it is under or fully constrained. In the MechanismEditor, the colour of the sketchelements in a Part agrees with the colour of its PartOutline. Therefore, in the MechanismEditor, each Part has a::
or a


Notes: The BasePart ALWAYS has a rectangular Green PartOutline, and, thus, when the MechanismEditor is active, sketchelements that are in the BasePart are ALWAYS Green. 