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A Magnetic-Joint pulls a Circular Profile to be in continuous contact with an Irregular Profile / Curve*. The Circular Profile and the Irregular Profile / Curve are in different Parts and kinematic-chains.
After you add the Magnetic-Joint, the motions of the two kinematic-chains are related by the contact between the Circular Profile and Irregular Profile / Curve.
* The shape of the irregular Profile can be:
•a Profile that you add to a sketch-loop
or
•a Curve that we calculate for you from a Point-Cloud
See also: Add Magnetic-Joint.
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Before you edit a Magnetic-Joint: 1.Click the Home key on your keyboard to move the MMA to zero. 2.Click a Magnetic-Joint FB in the graphic-area (see image to the left) The Magnetic-Joint element is in the Selection-Window 3.Right-click the Magnetic-Joint element in the Selection-Window 4.Click Edit element in the shortcut menu. OR 1.See How to Open a dialog
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Note: The icon of the Magnetic-Joint has three states in the graphic-area. |
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Enabled Magnetic-Joint - Found a solution |
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Disabled Magnetic-Joint - not active |
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Enabled Magnetic-Joint - Failed to find a solution |
![]() Magnetic-Joint dialog |
The Magnetic-Joint dialog has three separators: Following Options Radius Control Advanced |
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☑Enable Magnetic-Joint check-box The circular Profile is in continuous contact with the irregular Profile or Point-Cloud. ❑Disable Magnetic-Joint check-box. The circular Profile moves to the Base-Value (Linear or Angular position) as specified by the Motion-Dimension FB that was in continuous contact with the irregular Profile. |
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Outside The image shows the circular Profile |
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Inside The image shows the circular Profile
Note: The Magnetic-Joint INSIDE option does not operate as successfully as the Outside |
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Optionally, edit the effective radius of the Circular Profile. ❑Not Overriding Circle Radius (default) ☑Modify Circle Radius Enable the check-box if you want the Circular Profile to overlap the Irregular Profile. For example: Radius = 0mm When the Radius is 0mm, the center of the Circular Profile moves along the Irregular Profile as normal. Radius = 3mm When the Radius is 3mm (for example), the center of the Circular Profile is 3mm inside the Irregular Profile. This is useful if you use a CMM machine with a probe diameter that is different to the Cam-Roller, and the CMM software does not have Probe Compensation. When the CMM data does not compensate for the Probe Diameter, you would enable Modify Cycle Radius to recreate the contact between the irregular-Profile and the Cam-Roller. Offset Profile Radius = Radius of Actual Cam-Roller – Radius of CMM Probe R = Rcf – Rp Rcf = Cam-Roller Radius; Rp = CMM Probe Radius. |
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![]() 4 Possible Contact Solutions between Circular-Profile and a simple Irregular-Profile |
When you add a Magnetic-Joint, the Circular Profile uses numerical techniques to find a contact with the Irregular Profile. To humans, it is easy to see the contact that you want. But mathematically, even when the Irregular-Profile is a simple shape, there are usually a minimum of 4 solutions - see image to the left. MechDesigner may find the solution you want, or a solution you do not want, or even fail to find a solution at all. BEFORE YOU ADD THE MAGNETIC-JOINT - it is best to edit the Base-Value parameter in the Motion-Dimension FB, to put the Circular Profile within 0.5 x Radius of Circular-Profile. To Edit the starting position of the Circular-Profile
The factors in Advanced help us to find for you the solution you want. Reset Range Factor (default = 2) This factor limits the range of values within which to search for a solution for the Motion-Dimension, when the model is at the Home position (MMA = 0). A Reset Range Factor = 1 is equal to the 1 × Radius of the Circular Profile. The smaller Reset Range Factor, the nearer you should edit the Base-Value to put the Circular Profile to the Irregular-Profile before you add the Magnetic-Joint. Running Range Factor (Default = 1) MechDesigner must find a solution for contact between the Circular and Irregular-Profiles of the Magnetic-Joint contact at all steps in the machine-cycle. There are frequently at least 4 solutions - see image, left and top. However, the solution at any step in the machine-cycle should not be hugely different from the previous solution. Use the Running Range Factor to limit the range of Motion-Dimension values within which to search for a solution from the previous solution, at each step of the solution cycle. Running Range Factor = 1 is equivalent to 1 × Radius of Circular-Profile that is contact with the Irregular-Profile. Reduce the Running Range Factor if the Circular-Profile does not remain in contact with the Irregular-Profile, as you cycle the model. |
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