Edit a sketch-path or sketch-loop

A Sketch-Loop is a sketch that does not have breaks and the Points that join the sketch-elements are merged into one Point.

Generally, do not make a sketch-loop unless you intend to add to it a Profile/Extrusion (Solid) or a Motion-Path FB.

*About Merge-Points

Each Line or Arc you add to the graphic-area has a Point at each end.

In the Part-Editor, you have two options when you want the ends of two sketch-elements to move to the same position. You can:

make the Points coincident with Constraints toolbar > Add Coincident

- or -

merge the Points with Geometry toolbar > Merge-Points

In each case, the two Points show in the graphic-area as one Point. However:

Add Coincident Constraint does not remove a Point.
Add Merge-Points removes one Point

Why Merge-Points?

Use Merge-Points when you want to make an open or closed sketch-path.

You can use a sketch path for a Motion-Path FB

You can use a closed sketch-path (sketch-loop) for a Profile element.

tog_minus        Sketch-Loops with the Hover Technique and Merge-Points Tool

There are two ways to merge two Points into one Point:

Dynamically, as you add the sketch-elements, with the Hover Technique
Later, after you add the sketch-elements with Geometry toolbar > Merge-Points.

tog_minusWhy do Sketch-Loops fail?

Condition 1: Coincident Points, and not Merged

Points are not recognized as part of a sketch-loop when they are coincident.

You must merge the Points into one Point where each Line and Arc join.

Condition 2: Branches

You CANNOT merge three Points into one Point - for example, the ends of three Lines or Arcs - you have a 'Branch-Point'. A Branch-Point is not O.K.

You CAN merge two Points, then make a different Point become Coincident. This is NOT a Branch-Point.

Condition 3: Figures=of-Eight

A sketch-element can not cross another sketch-element in the same sketch-loop.

A sketch-element cannot osculate, or touch, another sketch-element in the same sketch-loop.

tog_minusExample sketch-loops



The Circle is a sketch-loop. A Circle is frequently used for a Cam-Follower.



Lines joined, with Points merged.


Lines and Arcs

Lines and Arcs, with Points merged.


Arcs and Arcs

Arcs and Arcs, with Points merged.


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