Objective of this Step:


How to add Lines and Arc sketch-elements to give a sketch-loop.
The important differences between Merged-Points and Coincident Points

About Sketch-Loops

A sketch-loop is a set of sketch-elements that are joined end-to-end, without a break. The shape of the sketch-loop is entirely up to the designer, of course.

The end-Point of each sketch-element must be merged to an adjacent end-Point.

When the end-Points of sketch-elements are merged in to a sketch-loop, we can do Solids menu > Add Profile

This command adds an Extrusion to the sketch-loop, to give a Solid in the graphic-area.

Difference Between Merged-points and Coincident-Points.

There are two different commands in the Part-Editor:

A)Add Geometry toolbar > Merge-Points
The command moves two Points to one position, and the command deletes one Point
Merge-Points is not an element.
You cannot delete the Merge-Points to recover one of the Points. You can undo with CTRL+Z, however.
B)Add Constraints toolbar > Coincident Constraint
The command moves two Points to one position* but the command does not delete one Point.
Coincident-Constraint is an element,
If necessary, you can delete the Coincident-constraint.

* A Coincident-Constraint can also move a Point to be coincident with a Circle, Arc and Line.


Add Geometry toolbar > Merge-Points for a sketch-loop and sketch-loop.

Add Constraints toolbar > Coincident Constraint for construction geometry.


Video: Hover Technique and Merge-Points command.

Using the Merge-Points tool and Hover Techniques

tog_minus        Merge-Points and Coincident Points

Add Coincident Constraint between Points

Add Coincident Constraint between Points

To Add Coincident Constraint

1.Add a Line as a 'Free Line'. It is near to a different sketch-element, but not joined to it.

With Add Coincident active:

2.Click the Point1s
3.Click the Point2s

Note: the Point1s must remain Red when you click Point 2s

Click the sketch-element to identify constraints

Click the sketch-element to identify constraints

To Delete Coincident Constraint

1.De-select all commands [click in a clear place in the graphic-area].

This removes all elements from the Selection-Window.

2.Click the Point in the graphic-area

The constraints that apply to the Point show in the Selection-Window.

In the Selection-Window:

3.Right-click the Coincident-Constraint
4.Click 'Delete' in the contextual-menu

Note: If you 'Click the sketch-element', the Constraints do NOT show in the Selection-Window.


tog_minus        Add Lines and Arcs to add the shape a Sketch-Loop

To make a sketch-loop, the end-Points of each adjacent sketch-elements must be Merged-Points

If necessary, start the Part-Editor to add sketch-elements.

Double-click the Part-Outline in the Mechanism-Editor

Use View Align if you prefer the X-axis of the new Part to be horizontal in the Part-Editor.


Icon-SE-Line Add Line


STEP 1: Click Add Line1s-red in the Geometry toolbar to the left of the graphic-area.
STEP 2: Drag the Line, approximately as shown2s

Step 2 is complete


Icon-SE-Arc Add Arc: Use two 'Drag' steps. See Add Arc video.


STEP 3: Click Add Arc1s-red in the Geometry toolbar to the left of the graphic-area.
STEP 4: Move above one of the Points2s at the end of the Line, until it becomes red, then...

STEP 1 of 'Add Arc'

STEP 5: DRAG 1: Mouse-Button-Down on the red Point, move your mouse-pointer to a different position, then mouse-button-up

The Mouse-button-down and mouse-button-up are the start-Point and end-Points of the Arc

STEP 2 of 'Add Arc'

STEP 5.Put your mouse-pointer between the start-Point and end-Point of the Arc.
STEP 6.DRAG 2: Drag again to approximate the radius of the Arc

Step 6 is complete


Do 'Add Line' and 'Add Arc' commands again two times more.

STEP 7: Add two more Lines and two more Arcs.

When you add the last sketch-element, hover above the end-Points of the last sketch-element the first sketch-element, to complete the sketch-loop

Optionally, Do not Hover + Drag as you add each sketch-element.

1.Add a sketch-element with the start-Point near to an end-Point
2.Use the Merge-Point tool to merge the start-Point and end-Point

If you miss the second point, then MechDesigner automatically de-selects the first Point.

You must select the two Points again.

The sketch is similar to the image to the left.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd