Behavior of a ball as it leaves a rotating rod.

[ptc-4748164]

In Mechanism, the rod rotates about the axis at its left end. As it rotates, the ball moves outward until it reaches the end of the rod. My problem is that I don't know of a way to assemble these parts so that once the ball leaves the rod, it behaves as it would in reality. Using a cylinder or slider the joint, the ball continues to move along the axis of the rod even when the two parts are no longer in contact.

Is there a way to set limits to constraints? For example, specify that the cylinder connection should deactivate or should not apply beyond a point defined at the end of the rod?

Or, is there a connection type I'm missing?

I realize I could accomplish my goals by using two separate assembles and Mechanism analyses, but I'm hoping for a more elegant solution.

Any help will be greatly appreciated.

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[TomD.inPDX]

Set a rotation limit on the rod. You can go past 360 degrees. Same as setting angle limits.

I'm not an expert at mechanism, but I know you can do that.

Someone will shime in here soon to show exactly where this is done.

[ptc-4748164]

Great idea!

Can anyone tell me if it is possible to set a condition so that the rod instantly stops rotating when datum point at the center of the ball and the datum point at the end of the rod are coincident?

Thanks!

[SylvainA.]

The solution is not to stop the rod rotation when the ball leaves it, because the ball's trajectory has not to be purely radial.

Don't forget the Coriolis effect. As it trotates, the rod "push" the ball tangentially and the centrifugal acceleration "pull" it radially.

Thus, when it leaves the rod, the ball's speed will have a radial component AND a tangential one.

This trajectory will be kept by the ball after leaving the rod (Newton's first law of motion).

[vzak]

"Is there a way to set limits to constraints? For example, specify that the cylinder connection should deactivate or should not apply beyond a point defined at the end of the rod?"

I do not think deactivation of constraint by condition exists, yet.

You may try Cam joint with liftoff - but you will need to simulate a CAM between the "inside" of the ball and the rod in some artificial way (likely with construction surfaces on both sides, 3 Cams to simulate Cylinder). Then with dynamics when Ball slides to the end ... it will fall down.

[TomD.inPDX]

The only limit I have found to date is the slot constraint. When the linked feature reached the end of the guide, it stops moving.

BTW: Welcome to the Community, Vladimir. Are you here on official capacity or is this your pastime? Either way, it is nice to have participation with an "inside" perspective. Looking forward to seeing many wonderful and insightful posts from you

[vzak]

Antonius, thanks for welcoming, hope I'll be visiting assembly / core topics from time to time. No official capacity, rather some good will and face to customer needs.

After all we spend plenty of time working on the product, so getting some to the end user make you only feel better