Objective of this Step

In Step 1.5, we specified the position of the rotating-Part with a Motion-Dimension FB. Importantly, the Part became a kinematically-defined Part when we added the Motion-Dimension FB

In this step, we will specify the Part's motion to be 'Constant-Angular Velocity'.

We will also learn how to connect wires from output-connectors to input-connectors of different FBs [Function-Blocks].

See also: How to Connect Function-Blocks


In MechDesigner, a Rocker is Motion-Part that might rotate continuously or oscillate. A Motion-Part that is a Rocker has its motion defined by the input to a Motion-Dimension FB.

It is the 'Rocker' element in the Kinematics-Tree.

In a Machine, a Crank is a Part that 'rotates continuously at constant speed' ; and a Rocker is a Part that 'oscillates back and forth'. It is not always a Motion-Part.

Terminology Reminder:

FB is a Function-Block.
'Connect a wire' is to 'drag a wire from the output-connector of a Function-Block to the input-connector of a different Function-Block'.
Motion-Values flow instantly from FB to FB.

Summary of this Step

1.Review the Kinematic-FBs, the Master-Machine-Angle, the Animation-Speed.
2.Add a Linear-Motion FB - also called a 'Clock'.
3.Connect a wire from the output-connector of the Linear-Motion FB to the input-connector of the Motion-Dimension FB.
4.Delete the wire
5.Add, connect and edit a Gearing FB to rotate the Part in a clockwise direction.



Tutorial 1: Step 1.7

Start the Part-Editor
Edit Length of a Part


Video of this Step

How to...Add a Linear-Motion FB and join the FBs with wires'

Kinematic Function-Blocks

Schematic of Function-Blocks

We use

Use Kinematic Function-Blocks to give motion-values to Motion-Parts and Motion-Points
Connect wires between Function-Blocks (FBs) from output-connectors to the input-connectors of a different Function-Block.

The schematic, to the left, shows how you can connect wires between the Function-Blocks.

Motion-Providers: have output-connectors. The motion-values are either the MMA or found from the motion of a Part or Point in a kinematically-defined chain.

Motion-Processors: use the motion-values from Motion-Providers as the independent variable for their internal function. You can actively design their functions.

Motion-Parts: are identified by Motion-Dimension FB. The Motion-Parts have their motion specified by the motion-values at the input-connector to the Motion-Dimension FB.

Motion-Points: are identified by a Motion-Path FB. The Motion-Points have their motion specified by the motion-values at the input-connector to the Motion-Path FB.

Tutorials Steps:

Add a Linear Motion FB; Connect to the Motion Dimension FB


STEP 1: Click Kinematic-FB toolbar > Linear-Motion FB [right of the graphic-area]
- or -
Click Function-Block menu > Add Linear-Motion
- or -
Right-click in the graphic-area, and select the Linear-Motion FB icon in the contextual-menu.


STEP 2: Click in the graphic-area.

MechDesigner adds the Linear-Motion FB1s-red to the graphic-area.

Put the Linear-Motion FB to the left of the Motion-Dimension FB. It is easier to connect the FBs together.


STEP 3: Connect Function-Blocks with a 'wire'2s.

See how: Connect Function-Blocks

The motion-values at the output-connector of the Linear-Motion FB are at the the input-connector of the Motion-Dimension FB.

The Motion-Dimension = Output from Linear-Motion FB + Base-Value of the Motion-Dimension FB


Cycle the kinematic-chain.

STEP 4: Click Run toolbar > Cycle icon
- or -
Click Run menu > Cycle
- or -
Press the 'C' key on your keyboard to start and stop the cycle command.

The Crank rotates one time with each Machine Cycle. Watch the red pointer under the Master-Machine-Angle move from 0 to 360 each time the Part rotates one time.

Rotate the Part in a Clockwise direction


As motion-values increase from 0 to 360, the Crank rotates in a counter-clockwise direction. Thus, the positive kinematic direction of an angle is the counter-clockwise direction.

To rotate the Crank in a clockwise direction, we will use a use a Gearing FB [I prefer to use the Gearing FB].

STEP 1: Click Kinematic-FB toolbar > Add Gearing FB
STEP 2: Click in the graphic-area.


STEP 1: Delete the wire between the Linear-Motion FB and the Motion-Dimension FB

To delete a wire:

1.Click the wire in the graphic-area
2.Click your 'delete' on your keyboard, our use the method in the Selection-Window
STEP 2: Connect the Linear-Motion FB to the Gearing FB, and the Gearing FB to the Motion-Dimension FB

Step 4 is complete


Now we can open the Gearing FB dialog-box

STEP 5: Double-Click the Gearing FB
STEP 6: Edit the Gearing Ratio parameter to -1.
STEP 7: Click OK.
STEP 8: Click Run toolbar > Cycle icon
- or -
Run menu > Cycle
- or -
Press the 'C' key on your keyboard

The Crank now rotates in a Clockwise direction.

Other Notes:

Master Machine Angle (MMA)

Master Machine Angle Indicator

Master Machine Angle in the Feedback Area


Revs: [Read-Only] box is a counter for each time the machine angle progressives from 0 to 360.

Pointer (): below the MMA scale, indicates the Master-Machine-Angle approximately

Machine Angle [Read/Write] indicates the Master Machine Angle exactly.

To edit the Master-Machine-Angle:

Approximately : Drag, to the left or right, with your mouse-pointer inside the Gold Area of the scale

Exactly : Enter a new value with keyboard in the Read/Write box.

Animation Speed

Animation Speed Slider

Animation Speed Slider in the Feedback Area

Edit the Animation-Speed

The Animation-Speed does not change kinematic results.

Drag, to the left or right, with your mouse-pointer inside the area of the scale

Edit the Simulation-Speed

The Simulation-Speed does change the kinematic results.

Use the Edit menu [or toolbar] > Machine Settings > Machine Speed.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd