Make the Motion-Part a Slider and not a Rocker

In this Tutorial:

1.We move the Motion-Dimension FB from the Pin-Joint to the Slide-Joint.

The 'Motion-Dimension -Rocker' will become a 'Motion-Dimension -Slider'

For convenience, we change the name of the mechanism from 'Crank-Slider' to 'Slider-Crank'.

2.We will look at the Kinematics Tree again.
tog_minusVideo of this Step

 

How to...

Add a Motion-Dimension to a Slide-Joint

Note the position of the Slider moves

tog_minusMove the Motion-Dimension FB from the Pin-Joint to the Slide-Joint

QST2-4-1

We must delete the Motion-Dimension FB at the Pin-Joint before we can add a new Motion-Dimension FB to the Slide-Joint.

The recommended method to delete an element is to:

STEP 1: Click the Motion-Dimension FB in the graphic-area.

The Motion-Dimension FB element will be in the Selection-Window

STEP 2: Right-click the Motion-Dimension FB in the Selection-Window,
STEP 3: Click 'Delete' in the contextual menu

Note: Alternatively, you can click an element so that it becomes red, then use your delete key on your keyboard.

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All of the Part-Outlines in the kinematic-chain should be Blue.

The kinematic-chain has one degree-of-freedom again.

Remember: Blue Part-Outlines are NOT kinematically-defined.

 

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You can drag the Part-Outlines if you like. It is not easy, but you can!

[To Drag: hover above the Part-Outline to make it Red, then Drag.

In this case, it is easiest if you drag the Part-Outline of the Part that was the 'Rocker'.

Move the Parts to a position that is similar to that shown in the image to the left.


(IMPORTANT NOTE FOR SOME USERS: Occasionally, you can only hover to make a Part-Outline Red by hovering over the Part-Outline at the arcs, near the start and end Points, at each end of the Part)]


MD-QST1.5-MotionDimensionFB

Now, we will add a new Motion-Dimension FB.

STEP 4: Click the Motion-Dimension FB1s-red in the Function-Block Toolbar.

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The Command-Manager shows you must select three elements from the graphic-area.

In the graphic-area: select a Pin-Joint or Slide-Joint, then two sketch-elements, to add a Motion-Part. One of the sketch-elements belongs to a kinematically-defined Part.

The top selection-box in the Command-Manager is the colour of dull pink 'English' skin, to show it is ready for you to select the element.

You do NOT need to click inside the selection-boxes.

Each time you select an element, the Command-Manager automatically advances to the next selection-box, ready for you to click the next element.

Only click in a selection-box if you want to clear [remove] the elements from the selection-boxes.

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STEP 5: The First Element: Click the Slide-Joint symbol

The Slide-Joint symbol you must click is one of the two rectangles that are along the length of each Line that specifies the Slide-Joint.

Please look at the image carefully to see the symbol of the Slide-Joint.

When you click a Slide-Joint symbol as the first element, the second and third elements you must select are Points. The Points must be at the ends of the Lines that specify the Slide-Joint.

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STEP 6: The Second Element: Click a Point at one end of the Line in the Base-Part

The first Point must be at one end of the Line in the Slide-Joint that is a kinematically-defined Part.

Here, it is the Point at the end of the Line that we added to the Base-Part.

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The second Point is at one end of the Line in the 'Free' Part. A Free Part has a Blue Part-Outline.

STEP 7: The Third Element: Click a Point at one end of the Line along the centre of the Added-Part

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STEP 8: Click OK in the Command-Manager to complete the command.

[You can also 'Right-click in the graphic-area' to complete the command. At the same time, the contextual menu will show]

The kinematic-chain is now kinematically-defined again. The Part-Outlines are Green.

The Part that was a 'Free' Part is now a kinematically-defined Part.

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STEP 9: Connect a wire from the output-connector  Motion FB to the new Motion-Dimension FB

A Motion-Dimension FB identifies the Part we will move with a specified motion.

Because the Part is a child to a Slide-Joint, it is a Slider.

tog_minusThe Motion-Dimension and Slide-Joint in the graphic area

Slide-Joint3

Slide-Joint BEFORE we add a Motion-Dimension FB

The Part we will move with a motion must have a Blue Part-Outline4s. This means the Part is NOT yet kinematically-defined.

We use a number of symbols to represent a Slide-Joint:

1s-red Wide Rectangular Box: that is along the Line of the moving* Part.

2s Narrow Rectangular Box: that is along the Line of the fixed* Part.

* Remember, the two Parts might move. Thus, this it is not a perfect rule. However, there is ALWAYS a Wide and a Narrow Rectangular Box.

3s Small Arrowhead: at the start of one Line that you select for the Slide-Joint.

The small arrowhead is the 'Positive Direction' of the Slide-Joint.

Slide-Joint4

Slide-Joint AFTER we add a Motion-Dimension FB

The Part-Outline4s is now Green. This means the Part is now a kinematically-defined Part

The small arrowhead, and the Wide and Narrow Rectangles are Green.

The symbols for the Motion-Dimension include:

1s-red The Dimension

2s The Dimension Line and the Extension Lines

3s The Motion-Dimension FB

As motion-values increase, the Slider will move in the positive-direction, as indicated by the small arrowhead.

tog_minusThe Kinematics Tree

The Kinematics-Tree has changed in Tutorial 2.

It has changed from a:

Rocker and RRR Dyad (Step 2.1)

to a:

Rocker and RRP Dyad (Step 2.3)

to a:

Slider and RRR Dyad (This Step)

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This kinematic-chain is a Slider and an RRR Dyad.

The Slider is one of the two Motion-Parts.

It has three elements:

a.Slide-Joint (<R8 Sliding-Joint)
b.Part
c.Mot-Dim Slider – a Motion-Dimension FB for a Slider

The RRR Dyad is one of the five Planar Dyads.

The RRR Dyad has five elements:

d.Pin-Joint
e.Part
f.Pin-Joint
g.Part
h.Pin-Joint

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