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lsilva1-Visitor
1-Visitor
March 9, 2015
Question

Inconsistent assemblies when no ground

  • March 9, 2015
  • 1 reply
  • 4279 views

I'm trying to make a ball bearing using the Pin assembly constraint

Sometimes I need the internal runner to spin, and other times the outer runner to spin, therefore, I cannot make one or another Default.

If I make it default, I get "You may not drag a model belonging to the ground body"

If I leave it Automatic, mechanica cries bricks when I try to put it on an assembly

(And I don't like the squares between the icon and the name of the part on the model tree)

CreoBearingNoGround.png

It's not only the bearing.

Sometimes I make a whole arbor loose so I can make it a pin on a third assembly

There's got to be a way to overcome this


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1 reply

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dgschaefer21-Topaz II
21-Topaz II
March 9, 2015

You need to have a fixed ground in your assembly, but that does not need to be a part. I have not tried this, but I would thing that you can create an assembly axis and use the pin connection on both components to the assembly axis and an assembly plane. Then both would be free to spin.

When placed in a higher level assembly, you would then fix either the inner or outer component to other parts in the assy as needed.

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    lsilva1-VisitorAuthor
    1-Visitor
    March 9, 2015

    Your logic is perfect, but Creo is cheat-resistant

    If I fix (Fix constraint) the object on the datums (if that's what you suggested), creo assumes that the object is the ground.

    If I Pin the object using the datums, the not-well-constrained square appears between the icon and the name of the part and subparts on the model tree.

    I will test this assembly on the bigger assembly, but I really think we are back to squat.

    L
    lsilva1-VisitorAuthor
    1-Visitor
    March 10, 2015

    I CAN make the inner race default. If I attach that race to an arbor (rigid constraints, not pin - just as expected in real life), and the arbor spins, the bearing will work normally: the inner will follow the arbor, and the outer will be fixed.

    I CANNOT do the above in a reverse order: Put the bearing somewhere, attached by the outer racer (which is pin), and After, attach the arbor to the inner. No: The arbor must hold the bearing.

    Still looking for a way to make everything Not default AND consistent.

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