IMPORTANT: Background to this Step.

Part's have two states

Unsolved Parts are not kinematically-defined. They have Blue Part-Outlines
Solved Parts are kinematically-defined. They have Green Part-Outlines

To be useful, the Part must be solved.

The state of the Part after STEP 1.4 is unsolved.

We will change its state to solved in this step of the tutorial.


To edit the default colours:

Application Settings > Graphics tab > Display Colours > Part Solved to Green and Part Unsolved to Blue.

Objective of this Step

To change the state of the Part to solved.

The Part becomes kinematically-defined.

Summary of this Step

Add a Motion-Dimension FB to a Part that is joined to another Part with a Pin-Joint.

Edit the Part's start position.

Note: we can also add a Motion-Dimension FB to a Slide-Joint - See Tutorial Step 2.5



Tutorial 1: Step 1.5

Add a Motion-Dimension FB
Edit a Motion-Dimension FB


btn_delkeywordA: Add a Motion-Dimension FB to a Part


STEP 1: Click:
Kinematic-FB toolbar > Motion-Dimension FB
- or -
Add menu > Add Motion-Dimension FB


In the Command-Manager, we must select three elements

We must select the three elements in the correct order (in sequence):

Red-14-1b Pin-Joint

Red-14-2 Solved-Line

Red-14-3 Free Line


Command Manager ready for selections

Command Manager ready for selections

Click the elements Red-14-1b Red-14-2 Red-14-3 in the image above

Red-14-1b Pin-Joint  - see Step 1.4

Red-14-2 Line in the Base-Part - see Step 1.3.

LineRed-14-2 is a child to the Base-Part. The Line is a solved-line because the Base-Part is a kinematically-defined Part.

LineRed-14-2 radiates (is a 'ray') from the Pin-JointRed-14-1b

Red-14-3 CAD-Line along the centre of the Added-Part - see Step 1.2

CAD-LineRed-14-3 is a child to the Added-Part. The CAD-Line is a free-line because the Added-Part is a Free Part .

CAD-LineRed-14-3 radiates (is a 'ray') from the Pin-JointRed-14-1b

Commandd Manager with selections

Commandd Manager with selections

STEP 2: Click OK-smallest in the Command-Manager.
Right-Click in the Graphic-Area - recommended short-cut.


The Motion-Dimension FB is now in the graphic-area.



The Motion-Dimension FB element has two features in the graphic-area:

Red-14-1b Function-Block

Red-14-2 Motion-Dimension Line - the arrowhead is the positive (increasing) direction of the motion-value.

Note: There are two different mouse-actions:

To move the FBRed-14-1b

To move the Motion-DimensionRed-14-2

Function-Block :

Hover(FB) + DRAG

Motion-Dimension Line :

CTRL + Hover(FB) + DRAG

Hover(FB)= move your mouse above the FB icon.

DRAG = Mouse-Button-Down, and move your mouse-pointer, Mouse-Button-Up


The colour of the Part-OutlineRed-14-3 is has changed from Blue to Green. Parts with Green Part-Outlines are kinematically-defined Part.
The design of the icon in the graphic-area is different to the icon in the Motion-Dimension FB in the Kinematic-FB toolbar.
Its design is similar to a Pin-Joint, which is to help you see that the Motion-Dimension FB specifies the angle of a Part.
btn_delkeywordB: Edit the Part's initial position - its Base-Value

To edit the Part's initial position, we must edit its Base-Value parameter in the Motion-Dimension dialog-box.

Motion-Dimension FB dialog-box

Motion-Dimension FB dialog-box

1.Double-click the Motion-Dimension FB in the graphic-area
or see How to open a dialog-box.

In the Motion-Dimension dialog-box:


The angle of the Motion-Dimension when a wire is not connected to the input-connector of the Motion-Dimension FB.

- or -

oBase-ValueRed-14-1b + Motion ValueRed-14-2

The current positional value of the Motion-PartRed-14-3

It is sometimes more useful to edit the current positional value than to edit its Base-Value.


It is possible to 'negate' the sense of the Base-Value and the Motion-Values


There are two parts to the Motion-Dimension in the graphic-area:

There is the FB Icon and the Dimension.

To move the:

Icon: Hover(FB) + Drag the Function-Block
Dimension: CTRL + Hover(FB) + Drag the Function-Block
btn_delkeywordThe Kinematics Tree

The Part, Pin-Joint and Motion-Dimension are the elements that make a Rocker. A Rocker is a Motion-Part.

If you explore the Kinematics-Tree, you can see the three elements that you need to give the Rocker kinematic-element.

Kinematic-Tree with Elements for a Rocker

Kinematic-Tree with Elements for a Rocker






Mot-Dim Rocker

btn_delkeywordImportant Kinematic Understanding and Terms
Degrees-of-Freedom (DOF) The number of coordinates that you need to specify the position and orientation of a Part.
oMobility = Degrees-of-Freedom – Number of Motion-Dimensions
oRocker: a Part joined with a Pin-Joint to a kinematically-defined Part. The angle of the Rocker is given by a Motion-Dimension FB.
oSlider: a Part joined with a Slide-Joint to a kinematically-defined Part. The position of the Slider is given by a Motion-Dimension FB.
Kinematically-Defined Part: a Part that is a child to a kinematically-defined chain
Kinematically-Defined Chain: a kinematic-chain that has Mobility equal to Zero.

A Completely Free-Part has three degrees-of-freedom (on a Plane)
A Pin-Joint removes two degrees-of-freedom.
A Motion-Dimension removes one degree-of-freedom.
3 – 2 – 1 = 0 ( DOFs )

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