Objective of this Step:

Add Line and Arc sketch-elements to give a sketch-loop.
Understand the difference between Merged-Points and Coincident Points

About Sketch-Loops

Line and Arc (and CAD-Line, Blend-Curve) sketch-elements each have an end-Point and start-Point. They can be joined in two ways.

The two Points can be made Coincident and Merged into one Point
The two Points can be made Coincident, but the two Points are remain

A sketch-Path is a set of sketch-elements in which their start-Points and/or end-Points are MERGED with each-other,

A Sketch-Loop is a Sketch-Path that is also made into a continuous loop.

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


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

Constraints toolbar > Add Coincident Constraint for construction geometry.


Video: Hover Technique and Merge-Points command.

Using the Merge-Points tool and Hover Techniques

tog_minusHow to make two Points Coincident or to Merge two Points

Add Coincident Constraint between Points

Add Coincident Constraint between Points

Note 1: PointsRed-14-1b and Red-14-2 are actually start-Points and/or end-Points.

Note 2: Red-14-1b must remain Red when you click Point Red-14-1b

1.Part-Editor: Click Geometry toolbar > Add Line: Add two Lines as a free Lines. Make their start-Points near to each-other.

Add Coincident Constraint

2.Part-Editor: Click Constraints toolbar > Add Coincident to make the two Point Coincident
a.Part-Editor: Click PointRed-14-1b
b.Part-Editor: Click PointRed-14-2


2.Part-Editor: Click Geometry toolbar > Merge-Points to merge the two Points:
a.Part-Editor: Click PointRed-14-1b
b.Part-Editor: Click PointRed-14-2
c.Click the graphic-area in a place with no other elements.

NOTE: You cannot delete the Merge-Points. It not an element. It actually removes a Point element.

Click the sketch-element to identify constraints

Click the sketch-element to identify constraints

Delete Coincident Constraint

Remove all elements from the Selection-Window.

1.Part-Editor: De-select all elements (click in a place that does not have any sketch-elements in the graphic-area).
2.Part-Editor: SHIFT+CLICK the start-Point or end-Point in the graphic-area

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

In the Selection-Window:

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

Note: If you SHIFT+CLICK the sketch-element (and not the Points), the Constraints that apply to the start-Point and end-Points 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 LineRed-14-1b to the left of the graphic-area.
STEP 2: Drag the Line, approximately as shownRed-14-2



Icon-SE-Arc Add Arc

STEP 3: Click Geometry toolbar > Add ArcRed-14-1b  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

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

Mouse-button down with your mouse-pointer between the start-Point and end-Point of the Arc.

Drag 2: Locate the radius of the Arc

Drag again to approximate the radius of the Arc


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

STEP 4: Add two more Lines and two more Arcs.

When you add the last sketch-element

STEP 5: Hover above the end-Point of the next-to-last sketch-element and the start-Point of 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.

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