Add Ball-Joint

<< Click to Display Table of Contents >>

Navigation:  MechDesigner Reference & User Interface > 2.2 Mechanism-Editor: > Kinematic elements >

Add Ball-Joint

Add Ball-Joint

You must do Add Ball-Joint two(2) times, to add a Ball-Joint to each end of one Part. The Part with a Ball-Joint at each end has the derived name of Connecting-Part.

One Ball-Joint joins the Connecting-Part to a Part in the active Mechanism-Editor.

And one Ball-Joint joins the connecting Part to a Part in a different Mechanism-Editor.


Terminology:

Ball-Joint :

A Ball-Joint makes a Point in one Part to be coincident with a Point in a different Part.

Connecting Part :

A Part with a Ball-Joint at its start-Point and at its end-Point

Completely-Free Part :

A Part with 3 degrees-of-freedom

Free Part :

A Part with 1 degree-of-freedom

See also: Ball-Joint dialog-box, Connecting Part Length and Diameter.

See also Ball-Joint configurations


Preparation

A typical preparation:

MD-GA-AddBallJoint-Prep1

Mechanism-Editor A

Usually, it is perpendicular() to the active Mechanism-Editor (b)

Part Red-14-3 in a kinematically-defined Chain(in GREY)

Mechanism-Editor B - the active Mechanism-Editor

two(2) PartsRed-14-4Red-14-5 that are not kinematically-defined

A typical arrangement has:

Part Red-14-4 : a Free-Part that is a Sliding-Part (with a Slide-Joint) or, a Rotating-Part (with a Pin-Joint)

Part Red-14-5 : a Completely Free Part (no joints)

Notes:

The Mechanism-Editors cannot be parallel to each other. They are usually perpendicular() to each other.

The Completely-Free Part joins to Part Red-14-4 and Part Red-14-3 to give the two(2) S joints in the S-S-R or S-S-P dyad. S is for Spherical-Joint

Try to estimate the length of the Completely-Free Part.

If the Completely Free Part is too short or too long, so that the Ball-Joints at each end cannot possible join with PartRed-14-4 and PartRed-14-3, you will not get the expected result.

Add Ball-Joint (two(2) TIMES)

Do Add Ball-Joint two(2) times. One time to each end of the Completely Free Part.

MD-GA-AddBallJoint-Prep2

STEP 1: Start the Add Ball-Joint command

Add Ball-Joint icon

Mechanism-Editor: Add menu > Mechanism sub-menu > Add Ball-Joint

OR

Mechanism-Editor: Kinematic elements toolbar > Add Ball-Joint

STEP 2: Add Ball-Joint #1

1.Make Mechanism-Editor B active.

2.Click PointRed-14-1b in the Completely-Free Part

3.Click PointRed-14-2 in the Free Part

If you cannot select the two(2) Points to add a Ball-Joint:

1.Toggle-Off the Auto-Update tool before you select PointRed-14-1b and PointRed-14-2

MD-GA-AddBallJoint-Prep3

When you do Add Ball-Joint #1 you can see the Ball-Joint symbol.

However, the PointsRed-14-1bRed-14-2 do not snap together.

They do snap together after you do Add Ball-Joint #2

 

MD-GA-AddBallJoint-Prep4

STEP 3: Add Ball-Joint #2

1.Click PointRed-14-3 at the other end of the Completely-Free Part

2.Click PointRed-14-4 - the Grey Point - in the kinematically-defined Part that is in Mechanism-Editor(A)

 

MD-GA-AddBallJoint-Prep5

Result - expected

The Ball-JointsRed-14-6Red-14-7 snap to the Points in Mechanism(A) and (B).

The Completely-Free Part and the Free Part are kinematically-definedRed-14-8


Note: If the arrangement of the two Connecting-Part and the Part that was the Free-Part is not correct, then see Change-Dyad Closure

MD-KT-AddBallJoint

Kinematics Tree

In the Kinematics-Tree,

The Ball-JointsRed-14-6Red-14-7 are the S Joints in the R-S-S Dyad (also P-S-S Dyad)

The letter S represents a Spherical-Joint.

 

Connecting-Part: Edit Length, Rod Diameter, Ball-Diameter

Notes:

You cannot add Solids to Connecting-Parts.

To edit the the symbolic diameter of the Ball-Joint - see Ball-Joint dialog-box

MD-GA-BallJoint-EditConnectingPart

Edit the Length of the Connecting-Part

Edit the Connecting-Part in the Part-Editor:

1.Mechanism-Editor: Double-click the symbol for the Connecting-Part

2.Part-Editor: Edit the Length dimension of the Connecting-Part

3.Exit the Part-Editor

 

 

MD-GA-BallJoint-EditConnectingPart-Dim

Edit the Symbolic Radius of the Connecting-Part

Edit the Connecting-Part in the Part-Editor:

1.Mechanism-Editor: Double-click the symbol for the Connecting-Part

2.Part-Editor: Add a Line or Circle

3.Part-Editor: Add a dimension to the Line or Circle

4.Exit the Part-Editor


Notes:

When you edit dimensions in a Part and the view is not the Front View, the CAD-Line, Axes, sketch-elements and dimensions may show in unusual places!

If you cannot add or edit a dimension, then do View | Front Plane.

Use Visibility toolbar > Show Solids in Mechanisms

 

MD-GA-BallJoint-EditConnectingPart-Show