Prepare the Rocker

In this Step we:

1.Add a Rocker – it is joined to the Slider.
2.Specify the Motion of the Rocker.

tog_minusPreparation 1E: Add a Rocker to the Slider


Edit the sketch to add a Point for the Pin-Joint of the Rocker.

STEP 1: Double-click the Slider to edit the sketch of the Slider.
STEP 2: Add a Line to the original Tool sketch, and Position it as shown to the left.
STEP 3: Close the Part-Editor

Quick Quiz:

Q: How can I make the new sketch Lines become Black (fully defined) even without Dimensions?

A: I have used the 'Mid-Point Constraint' to the new Vertical and Horizontal Lines.


STEP 4: Add a new Part
STEP 5: Add a Pin-Joint to the Point in the new sketch.
STEP 6: Add a Motion-Dimension FB to the Part to make it a 'Rocker'.
STEP 7: Edit the Base-Value of the Motion-Dimension to be -90º. (Double-click on the FB or Motion-Dimension arrow head)

Quick Quiz:

Q: For the Rocker Motion-Dimension, why did you reference the vertical short Line in the new sketch and not the horizontal Line?

A: The Horizontal Line does not 'radiate' from the Pin-Joint. It only passes through it. The Vertical Line does radiate from the Pin-Joint.


STEP 8: Edit the Rocker
STEP 9: Add a Line and Circle, as shown to the left.
STEP 10: Dimension them, as shown to the left.


STEP 11: Add the Motion and Linear-Motion FBs.
STEP 12: Connect the Function-Blocks
STEP 13: Cycle (ALT+C [C for R13.2+]) to preview the design.

You will notice the Slider moves back and forth by 100mm and the Rocker oscillate by 100º – at the same time.

Quick Quiz:

Q: Why is the motion the same?

A: We have linked the same Motion in MotionDesigner to the two Motion-Dimension FBs. The Rocker will use its own motion, not the Slider's motion.

tog_minusPreparation 1F: Edit the Motion for the Rocker


Add a new Motion in MotionDesigner

STEP 1: In MotionDesigner: Click Add Motion in the File Toolbar


STEP 2: Use Active-Motion-Settings > Motion tab > Motion Name to rename the motions to 'Slider' and 'Rocker'.



Add two Segments and edit the Blend-Points.

STEP 3: Use the 'Append Segment' Tool in the Segment Toolbar , twice to add two segments.
STEP 4: Edit the X Value of the Blend-Points to be as follows:0º, 30º, 110º, 140º, 230º, 260º, 360º
STEP 5: Edit the Y Position Values to be: 0, 0, 10,10, 20, 20, 20mm


STEP 6: Edit the Motion FB that we have connected to the Rocker,
STEP 7: Select 'Rocker' in 'Motion in MotionDesigner' to link the Rocker motion to the Motion FB
STEP 8: Cycle the Mechanism (ALT+C [C for R13.2+]) before we add the 2D-Cam


tog_minusPreparation 1G: Add the 2D Cam and Cam Follower


A Cam-Roller must be a Profile. Usually, the shape is circular.

See Also: Cam-Follower shapes

STEP 1: Click the Solids toolbar > Add Profile Command


STEP 2: Click the Circle in the 'Rocker' Part

There are two elements that we should not confuse.

The element that is in continuous contact with the Cam is a Profile element.

We give this element the name: Cam-Follower. If the shape is circular, then: Cam-Follower Roller.

The element to which we add the Cam-Follower Roller is a Part element.

We give this element the name: Cam-Follower Part.


STEP 3: Click Kinematic FB toolbar > 2D-Cam


STEP 4: Click the Part-Outline of the Base-Part
STEP 5: Click the new Cam-Follower Roller

The Cam looks like a bird's nest.

To help understand the shape, we can edit the 2D-Cam to hide Cam 1 and Cam 2, and show the Pitch-Circle-Path only.

STEP 6: Double-click the 2D-Cam.
STEP 7: Select the Pitch-Curve check box and clear Cam 1 and 2 check boxes.


The image to the left shows the Pitch-Curve of the Stationary 2D-Cam.

The only good thing is it is 'Stationary'!

Q: What is the problem?

A: The angle of the Cam-Follower Part (Rocker) is a function of the Master-Machine-Angle.

It should be a function of the position of the Slider.

Do you need more explanation?

See Step 6D1.3

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