﻿ MechDesigner Reference & User Interface > 2.2 Mechanism-Editor: > Kinematic elements > Add Ball-Joint

## Ball-Joint

 2x Ball-Joints in MechDesigner Rod-End Bearing 2 x Ball-Joint in SOLIDWORKS

Terminology:

 Ball-Joint : A Ball-Joint makes a Point in a Connecting-Part coincident with a Point in a different Part. You must add 2 x Ball-Joints to add a Ball-Joint to each end of a Connecting-Part : •1 x Ball-Joint between Points in different Parts that are in the active Mechanism-Editor. •1 x Ball-Joint between Points in different Parts that are in different Mechanism-Editors. Spherical-Joint : The kinematic and equivalent term for a Ball-Joint. Kinematics-Tree : Joints in a Dyad use the letter S for a Ball-Joint. For example, the R-S-S and P-S-S Dyads. Derived Names: Connecting-Part : A Part with a Ball-Joint at its start-Point and at its end-Point Part that is Completely-Free : A Part with 3 degrees-of-freedom (no joints) Part that is Free : A Part with 1 or 2 degrees-of-freedom

#### Preparation

A typical preparation:

A typical prerpation for Add Ball-Joint

Mechanism A

 Usually, Mechanism A is perpendicular(⊥) to Mechanism B •Part in a kinematic-chain that is kinematically-defined in the image is Pink

Mechanism B - the active Mechanism-Editor

 Three Parts: 1 × Part. It is kinematically-defined - typically the Base-Part. 2 × Parts. These Parts are not kinematically-defined. •Part : A Part that is free. It is joined to the Base-Part with a Pin-Joint. •Part : A Part that is Completely Free . It does not have joints before you do Add Ball-Joint.

Notes:

 •The Mechanism-Editors cannot be parallel to each other. They are most often perpendicular(⊥) to each other. •The Part that is Completely-Free will joint to Parts and to with Ball-Joints - these are two(2) S joints in the S-S-R or S-S-P dyads. S is for Spherical-Joint. •As you add the Part that is Completely-Free, try to estimate its length. If it is too short or too long, the Ball-Joints cannot join it to Part and Part - you do not get the expected result.

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

STEP 1: Start the Add Ball-Joint command

 Mechanism-Editor B is active. 1.Click Point at the end of the Part that is Completely-Free 2.Click Point at the end of the Part that is Free. If you cannot select the two(2) Points to add a Ball-Joint, disable, and try again.

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

However, Points do not snap together before you do Add Ball-Joint #2

 1.Click Point at the other end of the Part that is Completely-Free 2.Click Point - the Pink Point - at the end of the Part that is kinematically-defined in Mechanism-Editor(A)

Result

 The Ball-Joints snap to the Points in Mechanisms A and B. The Parts that were Completely-Free and Free are now kinematically-defined

If the arrangement of the Parts that were Completely-Free and Free is not correct, then see Change-Dyad Closure

Kinematics-Tree

 In the Kinematics-Tree, There is a new Dyad - the R-S-S dyad. The three Joints in the Dyad are: •Pin-Joint is the R joint - R is for Revolute-Joint •Ball-Joints are the S Joints - S is for Spherical-Joint

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

Notes:

You cannot add Solids to Connecting-Parts.

To edit the Length of the Connecting-Part

 1.Mechanism-Editor: Double-click the symbol for the Connecting-Part It is now open in the Part-Editor. 2.Part-Editor: Edit the Length dimension of the Connecting-Part 3.Exit the Part-Editor

To edit the Symbolic Radius of the Connecting-Part

 1.Mechanism-Editor: Double-click the symbol for the Connecting-Part It is now open in the Part-Editor. 2.Part-Editor: Add a Line or Circle 3.Part-Editor: Add a dimension to the Line or Circle 4.Exit the Part-Editor The dimension becomes the Radius of the Connecting-Part.

To edit the symbolic diameter of the Ball-Joint -

Notes:

 In the Part-Editor, when 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: do View toolbar > Front Plane. Also, to see the new Symbolic Radius: enable Visibility toolbar > Show Solids in Mechanisms