Step 2.3: Reconfigure as Crank-Slider

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Step 2.3: Reconfigure as Crank-Slider

Objective of this Step

To use different method of the user-interface to delete an element. In this case we will delete a Pin-Joint using the Selection-Window, Assembly-Tree and the Kinematic-Tree.

Introduce, the R-R-R Dyad

To replace a Pin-Joint with a Slide-Joint.

Summary of this Step

Delete a Pin-Joint using different procedures

Add a Slide-Joint

After this step, in the Kinematics-Tree, the R-R-R Dyad becomes an R-R-P Dyad.

Video 1: Delete Pin-Joint with different Procedures

 

Tutorial 2: STEP 2.3

Different ways to Delete a Pin-Joint

 

Video 2: Add Slide-Joint

 

Tutorial 2: STEP 2.3

To add a Slide-Joint

Delete the Pin-Joint

This part of the tutorials shows you how to delete an element from different areas of the interface.

In this case we delete a Pin-Joint, using contextual-menus, form the:

oSelection-Window

oAssembly-Tree

oKinematics-Tree

Note: It is also possible to delete joints in the graphic-area if you click it and the press with the 'delete' key on your keyboard.

Delete a Pin-Joint with the Selection Window

When you click one or more elements in the graphic-area, Assembly-Tree or Kinematics-Tree, they show in the Selection-Window.

You can delete the element using the Selection-Window.

Here, the element we will delete is a Pin-Joint.

GA-2.3-1

STEP 1: Delete the Pin-Joint

1.Mechanism-Editor: Click the Pin-Joint

Look in the Selection-Window.

SW-DeletePinJoint

It is possible, and even likely, that you will select more than one element.

In this case, we have clicked the Pin-Joint and a CAD-Line.


2.Selection-Window: Right-click the Pin-Joint in the Selection-Window.

A contextual-menu shows.

3.Selection-Window: Click Delete in the contextual menu

You will delete the Pin-Joint.

GA-2.3-2

After you delete the Pin-Joint, you will see that the Part-Outlines of the Parts become Blue.

Blue Parts are not kinematically-defined.


Notes:

MechDesigner will also delete the Motion-Dimension FB - it is bug!


 

GA-2.3-5a

Because we delete the Motion-Dimension FB when we delete the Pin-Joint  - which is a bug - we will add it again now.

STEP 2: Re-add the Motion-Dimension FB

1.Mechanism-Editor: Click Kinematic-FB toolbar > Add Motion-Dimension FB

Red-14-1b Click the Pin-Joint

Red-14-2 Click the Line in the Base-Part

Red-14-3 Click the Line along the short Part.

Click OK-tiny-11-15 in the Command-Manager

Delete a Pin-Joint from the Assembly-Tree

First, we will replace the Pin-Joint that we deleted above.


Note: Occasionally, you can only make a Part-Outline red if you hover above the arc near the start-Point of the Part.

GA-2.3-3

STEP 1: Replace the Pin-Joint

1.Mechanism-Editor: Click Edit menu > Undo, or the Edit Toolbar > Undo icon

- or -

1.Mechanism-Editor: : Do CTRL + Z key combination

- or -

1.Mechanism-Editor: Click Kinematic elements toolbar > Add Pin-Joint, | Click the two Points again again


In the graphic-area, you can see the Pin-Joint is in the model again. The Parts are Green Parts again.

Parts with Green Part-Outlines are Kinematically Defined Parts, again.


STEP 2: Delete the Pin-Joint - again!

1.Click to the left of the graphic-area - the Assembly tab

2.Explore the Assembly-Tree to find the Pin-Joint that you want to delete -

Here Pin-Joint7 - see Note 2 below.

Note 1:

The element you click in the Assembly-Tree becomes red in the graphic-area.

and

The element you click in the graphic-area is 'selected' in the Assembly-Tree (an Orange Square around its icon)

Note 2:

A Pin-Joint has two different symbols:

Dowel-Symbol The symbol for a Pin-Joint that uses the Base-Part, is similar to a dowel symbol in a technical drawing.

Pin-Joint The symbol for a Pin-Joint that does not use the Base-Part

3.Right-click the Pin-Joint in the Assembly-Tree - Dowel-Symbol

4.Select Delete in the contextual-menu.

In the image to the left, we can see the Part-Outlines of the Parts have become Blue.

The Parts are now not kinematically-defined.

Note: Occasionally, you can only make a Part-Outline Red if you hover above the Part-Outline at the arcs, near to the start-Point of the Part.

This is more difficult to do. We will try to resolve this problem.

AT-PinJoint

AT-Delete-PinJoint

GA-2.3-2

GA-2.3-5a

Because we delete the Motion-Dimension FB when we delete the Pin-Joint  - which is a bug - we will add it again now.

STEP 3: Re-add the Motion-Dimension FB

1.Click Kinematic-FB toolbar > Add Motion-Dimension FB

Red-14-1b Click the Pin-Joint

Red-14-2 Click the Line in the Base-Part

Red-14-3 Click the Line along the short Part.

Click OK-tiny-11-15 in the Command-Manager

Delete a Pin-Joint from the Kinematic Tree

GA-2.3-3

STEP 1: Re-add the Pin-Joint

1.Use Edit menu > Undo, or the Edit Toolbar > Undo icon

- or -

1.Use the CTRL + Z key combination.

The Parts-Outlines are now Green, again, as they are now kinematically-defined.

KT-RRR-PinJoint

STEP 2: Delete the Pin-Joint - again!

1.Click on the Kinematics tab in the Project-Explorer to open the Kinematics-Tree.

2.Expand the R-R-R dyad.

You can see the list of three Pin-Joints and two Parts.

Note 1: The more academic term for a Pin-Joint is a Revolute Joint. Thus, R for three Revolute Joints in the R-R-R Dyad.

3.Click the Pin-Joint that has the Grounded Pin-Joint Symbol

Note 2: When you select an Element, Dyad, or Kinematic-Chain in the Kinematics-Tree, it becomes red in the graphic-area.

SW-PinJoint-2Points

The Pin-Joint is in the Selection-Window.

Note 3: When you select the Pin-Joint in the Kinematics-Tree, you see the Pin-Joint also in the Selection-Window

GA-2.3-2

Again, you will see, as in the image to the left, the Part-Outlines are Blue (see Step 2.1)

Blue Parts are not kinematically-defined.


 

GA-2.3-5a

Because we delete the Motion-Dimension FB when we delete the Pin-Joint  - which is a bug - we will add it again now.

STEP 3: Re-add the Motion-Dimension FB

1.Click Kinematic-FB toolbar > Add Motion-Dimension FB

Red-14-1b Click the Pin-Joint

Red-14-2 Click the Line in the Base-Part

Red-14-3 Click the Line along the short Part.

Click OK-tiny-11-15 in the Command-Manager


A Slide-Joint.

The kinematic-chain in the model has Pin-Joints only.

To remind us:

A Pin-Joint is between two Points

Each Point must be a child to a different Part

Imagine Point 1 is the Bearing Shaft (on Part 1), and Point 2 is the Bearing Housing (on Part 2).

Introducing the Slide-Joint

A Slide-Joint is a joint between two Lines

Each Line must be a child to a different Part

Imagine Line 1 is a Slide-Rail (on Part 1), and Line 2 is a Slide-Block (on Part 2)

Add a Line to the BasePart

To add a Slide-Joint, we need a Line in two different Parts. We are going to add a Slide-Joint between an Added-Part and the Base-Part.

We will use:

The CAD-Line along the center of an added Part.  

A new Line in the Base-Part,

Note: We can use any Line we add to a Part and the Base-Part.

GA-2.3-4

STEP 1: Add a Slide-Rail to the Base-Part. We will edit the Base-Part to add a new Line

1.Mechanism Editor: Double-Click the rectangular Part-Outline to edit the Base-Part with the Part-Editor.

2.Part-Editor: Geometry toolbar > Add Line | Drag from left to right and slightly upwards to add Red-14-1b (the drag direction becomes important later)

3.Part-Editor: Geometry toolbar > Add Dimensions to specify the position of the Line

When the Line is fully defined - Green in my color scheme to the left.

4.Exit the Part-Editor...

To exit the Part-Editor, we can use the Edit Part icon above the Geometry toolbar (left of Graphic-area).

4....continued... Click the Edit Part icon, Icon-EditPart, to deselect it, and return to the Mechanism-Editor.


Note:

The Base-PartRed-14-2 is ALWAYS a kinematically-defined Part.

The LinesRed-14-1b are Green in the Mechanism-Editor because each Line is a child to a kinematically-defined Part – the Base-PartRed-14-2

GA-2.3-8

Add the Slide-Joint

Icon-AddSlideJoint

STEP 1: Add a Slide-Joint

GA-2.3-9

1.Mechanism-Editor: Click Kinematic-elements toolbar > Add Slide-JointRed-14-1b

A Slide-Joint needs two Lines.

2.Mechanism-Editor: Click the CAD-LineRed-14-2 along the Part

3.Mechanism-Editor: Click the LineRed-14-3 that we have added to the Base-Part

See the mouse-pointer in the image to the left.


The Lines are now collinear. There is a Slide-Joint (see below: The Slide-Joint in the Graphic-Area)

The Slide-Joint has replaced the Pin-Joint.


STEP 2: If needed: Change the Dyad-Closure

We look at Dyad Closures in much more detail in the next STEP 2.4 Dyad Closures

There are four possible closures when you add the Slide-Joint:

The Parts may jump to a different position

AND / OR when you use Run menu (or toolbar) > Cycle, the Parts in the Dyad do not move as the Rocker moves.

1.Mechanism-Editor: Click Kinematic-element toolbar > Change Dyad Closure

2.Mechanism-Editor: Click on of the two Parts in the Dyad

3.Click OK-tiny-11-15 in the Command-Manager

Do 1-3 again, and again, until the Parts are in the same position as the image to the left.


STEP 3: Expand the Kinematics-Tree

The Parts that were in the R-R-R Dyad are now in an R-R-P Dyad.

The three Joints in the R-R-P Dyad are:

Two Revolute-Joints, (R-R-P), - or two Pin-Joints

One Prismatic-Joint (R-R-P) - or one Slide-Joint

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GA-2.3-11

The Slide-Joint in the graphic area

GA-2.3-12

There are a three symbols to represent a Slide-Joint.

In the image we can see:

Red-14-1b A Wide rectangular box: It is along the CAD-Line of the sliding- Part.

Red-14-2 A Narrow rectangular box: It is along the Line of the Base-Part.

Red-14-3 A small arrowhead at the start-Point of one of the Lines that you select for the Slide-Joint

The arrow-head shows the Positive Direction of the Slide-Joint.


The Positive Direction is important if you want to add a Motion-Dimension with the Slide-Joint.