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My scotch yoke construction does not animate

hansrudolfhansrudolf Member Posts: 52 ✭✭
I want to thank MichaelPascoe for his example of a scotch yoke mechanism (in my other discussion), but I'm a bit lost about the complexity of this example.
Anyway, after several unsuccessful attempts, I managed to finish my construction - or so I thought. But when I try to rotate the central part, the whole construction rotates. The same also with the other movable parts, nothing moves separately.
As it is I can build this construction even if I can't animate the assembly, but I would like to know where I did wrong.
Here is my construction, maybe it is necessary to rotate it upside down to see the innards.

https://cad.onshape.com/documents/ff7f5fa2fc7a768fbd9d9822/w/00dacc37432520257cec5aa4/e/9dc07b81a8306ce1a0d4aff6

Many thanks,
Hansrudolf

Comments

  • S1monS1mon Member Posts: 2,986 PRO
    You need to either fix one part or mate one to the origin, otherwise all the parts are floating in space.
  • glen_dewsburyglen_dewsbury Member Posts: 782 ✭✭✭✭
    Fix the base as S1mon says.
    Not sure what the slider device is supposed to do?
    Pin/Slot mate is a better option than tangent.
    Animate the revolute mate in this example and the yoke will move freely in it's slot.
    https://cad.onshape.com/documents/549f5b1cd9bd3231e3b38f04/w/31641f46911206b1e70c8eec/e/d6bafc5a91c5026e1f42a3f9
  • hansrudolfhansrudolf Member Posts: 52 ✭✭
    Many thanks for your answers, S1mon and Glen.

    I remember that in one of the training courses it was said that the first part in an assembly is automatically fixed. Maybe it misinterpreted this. But now when I fix the housing of the apparatus, all works as intended.
    My experiments with pin/slot never worked.
    I see you could do it, now have to find out why  I was not successful.
    The slider device is there to change the throw of the eccentric. In real life, it is fastened with a part not shown in my construction.

    I'm always astonished about the help an Onshape user can get here. Even if he is just a simple amateur mechanic.

    Kind regards,
    Hansrudolf

  • glen_dewsburyglen_dewsbury Member Posts: 782 ✭✭✭✭
    @hansrudolf
    Knowing pin/slot was the right choice was the start for me. Not sure when I last used it and had to go to the help file. Make sure the direction is oriented correctly. In this case no limits were needed. Select the pin first then the center of the slot. Hover over the shuttle then hold the shift key will allow selection of the slot center.
    I also added a configuration variable with min/max to set throw for the slider.
    Helping others can be a good refresher on things not used a lot.
    https://cad.onshape.com/documents/549f5b1cd9bd3231e3b38f04/w/31641f46911206b1e70c8eec/e/d6bafc5a91c5026e1f42a3f9
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