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_minusMerge-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 Point2s

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 also show in the Selection-Window.


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

Step 2 is complete


Icon-SE-Arc Add Arc:

STEP 3: Click Geometry toolbar > Add Arc1s-red  to the left of the graphic-area.

To add an Arc, you must Drag two times. See Add Arc video.

Drag 1: Add Start-Point and End-Point of the Arc

STEP 3: Mouse-button down over an end-Point, move your mouse-pointer, mouse-button-up.

Drag 2: Locate the radius of the Arc

STEP 4: Put your mouse-pointer between the start-Point and end-Point of the Arc.
STEP 5: Drag again to approximate the radius of the Arc


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

STEP 7: Add two more Lines and two more Arcs.
STEP 8: 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.

If you miss a Point as you add the sketch-elements, CTRL+Z or use Geometry toolbar > Merge-Points to merge two Points into one Point.

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