### What is a Magnetic-Joint?

A Magnetic-Joint pulls a circular Profile, that is in one Part, to be in continuous contact with an irregular Profile, that is in a different Part.

The shape of the irregular Profile is a Curve (which is calculate from a Point-Cloud) or the shape of a Profile.

### Why use a Magnetic-Joint?

A frequent application of the Magnetic-Joint is to reverse-engineer a cam, and to find the motion of a cam-follower from the shape of the cam.

### Prepare the Magnetic-Joint

KINEMATIC-CHAIN 1:

Irregular-Profile : a Curve calculated from a or a Profile defined by sketch-elements.

Irregular-Profile : is a child to any Part that is in a kinematically-defined chain, or it may be child to the Base-Part.

In this model, the irregular-shape is a child to Part, which is a Rocker/Crank.

KINEMATIC-CHAIN 2:

Circular-Profile : a Profile.

Motion-Dimension FB specifies the position of a kinematically-defined chain, in which the Circular-Profile is a child to Part

In this model, Motion-Dimension FB specifies the position of Part in which the Circular-Profile is a child.

Notes:

 • Part and Part will usually move relative to each other.
 • Part and Part will usually be in different kinematic-chains.
 • Part and Part might be in one kinematic-chain, but with at least two Motion-Dimension FBs.

After you do Add Magnetic-Joint, Motion-Dimension FB, becomes driven by the Magnetic-Joint

RULES

Shape of the Irregular-Profile

 1 Preferably, you apply a Tangent Constraint between the sketch-elements that define the shape of the Irregular-Profile.

Immediately before you do Add Magnetic-Joint

 1 Home the model with the ALT+H key combination.

With respect to which surface of the Irregular-Profile you want the Circular-Profile to be in contact : its Outside-Surface or its Inside-Surface:

 2 Edit Motion-Dimension FB | Base-Value to move the Circular-Profile so that the:
 a) - Normal distance from Circular-Profile to the Irregular-Profile < 0.5 × Radius of the Circular-Profile

or, equivalently, the:

 b) - Normal distance from the Centre of the Circular-Profile to the Irregular-Profile  < 1.0 × radius of the Circular-Profile

Toolbar :

Machine Elements Toolbar

Machine Elements Toolbar : Add Magnetic-Joint icon

Dialog :

Magnetic-Joint dialog-box

ELEMENTS:

The Part on which the Irregular-Profile is a child.

The Irregular-Profile - a Profile or a Curve calculated from a Point-Cloud

The Motion-Dimension FB that will become driven by the Magnetic-Joint and the contact between the Circular-Profile and Irregular-Profile.

The Circular Profile

The Part to which the Circular-Profile is a child.

 1 Click Run menu > Home  ( or the ALT+H key combination).
 2 Edit the Motion-Dimension FB | Base-Value to move the Circular-Profile to be near to Irregular-Profile
 3 Click Machine elements toolbar > Add Magnetic-Joint
 4 Click the Irregular Profile
 5 Click the Motion-Dimension FB
 6 Click Profile
 7 Click in the Command-Manager

RESULT:

 • The Magnetic-Joint pulls the Circular-Profile to be in contact with the Irregular-Profile.
 • A Point Symbol is at the contact.
 • The Magnetic-Joint FB shows near to the Point-Symbol
 • A Magnetic-Joint icon is near to the Motion-Dimension FB that becomes driven by the Magnetic-Joint.

Notes:

The Magnetic-Joint does not use closed-form mathematical equations. The position of the Magnetic Driven-Part is solved with iterative, root-finding techniques.

The Magnetic-Joint may fail if the Circular-Profile and Irregular-Profile cannot stay in continuous contact for a complete machine-cycle.

Wait, if you have many Magnetic-Joints in one model.