Objective of this Step:

Learn:

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

About Sketch-Elements and Sketch-Loops in the Part-Editor

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.

It is important that the end-Point of each sketch-element is joined to an adjacent end-Points with as Merged-Points.

Only when the Points are merged, will MechDesigner recognize the Line and Arc sketch-elements we add as a sketch-loop.

Then, we can do Solids menu > Add Profile to add an Extrusion to a sketch-loop, to give a Solid in the graphic-area.

tog_minus        About 'Merge-Points' and 'Coincident Constraint'

The difference between the two commands:

•Merge-Points : makes two Points become one Point. After, you cannot delete the 'Merge-Points' to recover one of the Points. [You can 'undo', however].
•Coincident Constraint : moves two Points to the same position. Two Points become in one position. After, you can delete the 'Coincident' element.

Merge Points

To 'Merge-Points'

Video: Hover Technique and Merge-Points command.

➜

Using the Merge-Points tool and Hover Techniques

To recover the two Points that are 'merged' to one Point.

1.Do immediately CTRL+Z .
2.Add the two sketch-elements again but use Add Coincident Constraint to move the Points together.

Coincident Points

Use a Coincident Constraint for construction geometry.

For example, to position Points for Pin-Joints
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, and then
3.Click the element2s to which you want to make it coincident - for example a different Point.

Note: the first Point must remain Red when you click Point2
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.

SW-Delete-Constraint

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.

GA-Sketch-Loop1-AddLine

Icon-SE-Line Add Line

 

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

Step 2 is complete

GA-Sketch-Loop2-AddArc

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-side 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

GA-Sketch-Loop3-

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