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Animating Assemblies

james_alfordjames_alford Member Posts: 17
Good evening.

The linked assembly shows an arm with a rounded face and a cog wheel. The intention for the actual device is that when the arm is activated, the rounded face pushes the wheel around. Eventually, the moment will be limited so that it only moves by one tooth at a time.

Using revolute mates, I can make the wheel rotate and I can make the arm move. However, I should really like to be able to make the arm move wheel when the arm is moved. Is this possible? I have tried, but cannot see how to do it.


Thank you.



  • james_alfordjames_alford Member Posts: 17
    I have tried again, this time using the gear relation between the two revolute mates. It works after a fashion, but each time that I create the relation, it off-sets the arm from its starting point. How can I prevent this from happening?

  • philip_thomasphilip_thomas Member, Moderator, Onshape Employees, Developers Posts: 1,381
    @james_alford - Hello!

    Mating mechanisms like this requires a little bit of thought and knowledge.
    Here are some smarts :)
    • All mates have a 'zero' position - mate relations are with respect to the zero (or 'reset') so when you add a mate relation, the parts could move 'unexpectedly'.
    • You can 'reset' any mate by RMB/reset.
    • The situation can exist where it is not possible to 'reset' all mates (something always moves) - nothing bad has happened.
    • To get the mechanism to be at its 'zero' state with all mates 'reset' - you need to adjust the mate connectors (either explicit or implicit). Edit one of the pairs of mate connectors in the mate of interest and adjust the resting state so that (for instance) the teeth of cogs mesh.

    I hope this helps :)
    Philip Thomas - Onshape
  • james_alfordjames_alford Member Posts: 17

    Thank you for the suggestion. I have had another attempt, resetting the zero positions of the parts. However, no matter what angle I put in for the individual mates, as soon as I use the gear relationship to link them, it overrides the settings to those shown in the picture below. I am trying to get the rounded face on the arm to just toucha vertical face on the gear wheel.

    I should appreciate any furher suggestions.

    Thank you.


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