Mechanism | Add Slide-Joint

Kinematic Elements Toolbar : Add Slide-Joint icon [<<left of graphics-area]

Menu:

Add menu > Mechanism sub-menu > Add Slide-Joint

Dialog-Box:

None

IMPORTANT: Slide-Joints and Force calculations : to correctly calculate reaction forces, the length of the two Lines in a Slide-Joint should equal to the Slide-Rail and Slide-Bearings in your actual machine design.

The Slide-Joint symbol in the graphic-area is:

Narrow Rectangular Box - its length is equal to the length of Line '1' you select for the Slide-Joint

Wide Rectangular Box - its length is equal to the length of the other Line '2' you select for the Slide-Joint

Arrowhead to show Positive-Direction* - is at the start-Point of one of the two Lines you select for the Slide-Joint

* Positive-direction is important when you add a Motion-Dimension FB to the Slide-Joint.

See Positive direction of Slide-Joints and Motion-Dimension

See Also: Add Pin-Joint, Add Ball-Joint, Add Motion-Dimension FB

1. A Line* that is a child to a Free-Part 2. A Line* that is a child to: • a different Free-Part - or - • a kinematically-defined Part.

In this image: line is in the Base-Part [Rectangular Part-Outline is not-shown], which is always a kinematically-defined Part, and Line is the CAD-Line along the centre of an Added-Part.

* Line or CAD-Line

STEP 1: Click Add Slide-Joint

STEP 2: Click the two Lines:

1. Click a Line in a Free-Part 2. Click a Line in a different Part

If the Select-Elements dialog-box opens, you have clicked more than two Lines. 1. CTRL+Click the two Lines [in two different Parts] in the Select-Elements dialog box. 2. Click to close the Select-Elements dialog-box See also Slide-Joint Special Case.

STEP 3: Complete the command

Assembly-Tree

A new Slide-Joint

Kinematics-Tree

In this case, the new Slide-Joint in an 'Unsolved Mechanism' .

One of the Parts in the Slide-Joint above is not kinematically-defined, and has a Blue Part-Outline.

Assembly-Tree

A new Slide-Joint

Kinematics-Tree

In this case, the new Slide-Joint in an Unsolved-Mechs as the Part-Outline is Blue in the model above

Frequently, a design needs two, or more, collinear Slide-Joints.

To add a Slide-Joint, we must select two[2] Lines, with one line for two different Parts.

However, we must be careful as to which two Lines we select when we want the new Slide-Joint [#2] to be collinear with a different Slide-Joint [#1].

From a total three Parts and Lines, we must decide which two Lines we want to select for each Slide-Joint.

Assuming that Slide-Joint #1 is between Lines 1 & 2 [in Parts 1 & 2], then there are two options for Slide-Joint#2

Option A: Slide-Joint#2: between Line 3 & 1 [in Parts 3 & 1]

Option B: Slide-Joint#2: between Line 3 & 2  [in Parts 3 & 2]

Option A and Option B becomes important when you need to add Motion-Dimension FBs to specify the motions of one or the two Parts.

The image to the left shows:

•	Line is in a Part [obviously] but its Part-Outline is not in the image.

•	CAD-Line along the centre of Part, [but we can see because it is collinear with Line]

B.	Completely-Free Part , which includes a CAD-Line along its centre.

Note:

A minimum of one Part must be a Free-Part.  However, one Part, two Parts, or all three Parts may be Free-Parts.

STEP 2:

Click the CAD-Line along the center of the Completely-Free Part

Note:

The Slide-Joint does not need to be with the CAD-Line.

Generally, a Slide-Joint can be with any Line in a Part.

STEP 3:

Click the two Lines in the Slide-Joint.

Notes:

Now we have clicked a total of three Lines.

The Slide-Joint is between two Lines only.

Thus, there is ambiguity as to which two Lines you want for the Slide-Joint.

'Ambiguity': term to use when MechDesigner cannot be sure as to which elements you want to select.

Select-Elements dialog-box

When there is ambiguity about the Lines you want to select, the Select Elements dialog-box opens.

Notes: Very frequently, to add a new element you must select other elements.

If you anticipate that there might be ambiguity as to which elements might be selected, we recommend, whenever possible, you:

In the Select-Elements dialog-box, the element at the top of the list is always the first element you select.

As we did follow our recommendation, the Line at the top of the list is Line is at the top of the list of elements - it has the element-name of CAD-Line2

We definitely want to select CAD-Line2 [at the top of the list] for the new Slide-Joint.

The ambiguity is which of the other two Lines we want to select for the new Slide-Joint.

To select the Lines

1.	key down - do this before you click the Lines in the box.

Generally, mathematically, you can combine two elements from three elements in three possible ways. 1&2; 2&3; 3&1

However, MechDesigner will select only those elements that you can combine to add the new element.

Thus, you can select:

- or -

However, you cannot select:

Why? MechDesigner knows there is a Slide-Joint between these two Lines already.

In the Select-Elements dialog-box.

1.

key down

STEP 5:

Click in the Select-Elements dialog-box.

The Select-Elements dialog-box closes.

The two Lines become collinear.

If they do not become collinear...

The two Lines become collinear to add a new Slide-Joint,

Now, there are two Slide-Joints and three Lines that are collinear.