What is a Slide-Joint?

MechDesigner definition: A Slide-Joint makes a Line in one Part to be collinear with a Line in a different Part. The Lines can move along each other.


IFTOMM Kinematic definition: a Slide-Joint makes an axis in one Part become collinear with an axis in a different part, but allows the axes to slide along each other.


Note: Styling: Charcoal, Dark,  Edit menu > Application-Settings > Graphics tab > Display Colours :  [Background : White] ;  [Part-Unsolved : Blue] ; [Part-Solved: Green] ;[ Joint-Solved : Green] ; [Joint-Unsolved : Blue]

Add Slide-Joint

Add Slide-Joint icon

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.

GA-SlideJointDefined

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

two[2] rectangles - a wide and a narrow rectangle.

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

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

3s 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

Preparation:

Before you can do Kinematics-elements toolbar > add Slide-Joint you must have a minimum of two Parts, and one Line* in each Part. A minimum of one Part must have a blue Part-Outline.

GA-AddSLide-Joint-Prep1

1.A Line*1s-red that is a child to a Free-Part
2.A Line*2s that is a child to:
a different Free-Part

- or -

In this image: line2s is in the Base-Part [Rectangular Part-Outline is not-shown], which is always a kinematically-defined Part, and Line1s-red is the CAD-Line1s-red along the centre of an Added-Part.

* Line or CAD-Line

Add Slide-Joint:

GA-AddSlideJoint-0

GA-AddSlideJoint-1

STEP 1: Click Add Slide-Joint

Icon-AddSlideJoint

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

Kinematic Elements Toolbar : Add Slide-Joint icon

STEP 2: Click the two Lines:

1.Click a Line1s-red in a Free-Part
2.Click a Line2s 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 OK-tiny-13-17 to close the Select-Elements dialog-box

See also Slide-Joint Special Case.

STEP 3: Complete the command

If the two Lines do not snap together:

1.Click the graphic-area

The two Lines become collinear.

KT-SlideJoint

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.

VIDEO: Add Slide-Joint - Simple-Case

 

How to...

Add a Slide-Joint

[R14]

 

Kinematics-Tree

KT-SlideJoint

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

tog_minusSpecial Case: Two or more collinear Slide-Joints

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.

GA-AddSlideJoint-SC1

The image to the left shows:

A. Slide-Joint: a joint of two collinear Lines
Line1s-red is in a Part [obviously] but its Part-Outline is not in the image.
CAD-Line along the centre of Part2s, [but we can see because it is collinear with Line1s-red]
B.Completely-Free Part3s , 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.

Icon-AddSlideJoint

STEP 1: Click Kinematic-elements Toolbar > Add Slide-Joint

GA-AddSlideJoint-SC2

STEP 2: Click the CAD-Line4s along the center of the Completely-Free Part

Note:

The Slide-Joint does not need to be with the CAD-Line4s.

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

GA-AddSlideJoint-SC2A

STEP 3: Click the two Lines5s 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.


Dialog-Select-Elements-SlideJoint

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:

click an element that does not have ambiguity before
click an element that does have ambiguity.

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


 

Dialog-Select-Elements-SlideJoint2

As we did follow our recommendation, the Line at the top of the list is Line4s 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 Lines5s we want to select for the new Slide-Joint.


To select the Lines

1.Ctrlb key down - do this before you click the Lines in the box.
2.Select all of the Lines we want to use for the new Slide-Joint

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:

CAD-Line2 and Line3 [image above]

- or -

CAD-Line2 and CAD-Line [image left]

 

Dialog-Select-Elements-SlideJoint3

Dialog-Select-Elements-SlideJoint4

However, you cannot select:

CAD-Line2 and CAD-Line [image left]

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

GA-AddSlideJoint-SC3

In the Select-Elements dialog-box.

STEP 4: Select the two Lines:
1.Ctrlb key down
2.Select all Lines in the Select-Elements dialog-box to do Add Slide-Joint
STEP 5: Click OK-tiny-11-15 in the Select-Elements dialog-box.

The Select-Elements dialog-box closes.

The two Lines become collinear.

If they do not become collinear...

STEP 6: Click the Graphic-Area

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

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

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