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Multiple fasten mates?

jason_traudjason_traud Member Posts: 13
I've made a wheel and a hub and I'm having trouble getting all the holes to line up. It appears that I can only use a single fasten mate on the two parts but it only lines up one hole. Am I using the feature wrong or is there a better way of doing this?



https://cad.onshape.com/documents/4b63c675a45625f191cf7db0/w/1c40f3983f3f616177f414e1/e/4e36f1f8f30c889943840714

Best Answers

Answers

  • edward_petrilloedward_petrillo Member Posts: 57 EDU
    You can fix this in the assembly by using a revolute mate at the center of the wheel and hub and a cylindrical mate on one of holes, but you could avoid the problem entirely by using a different approach to modeling the components.

    You've chosen to create the wheel in one parts studio and the hub in another, and as a result the geometries of the two parts are not linked to each other.  The six-hole pattern of holes in each of the parts is at a slightly different angle to "true north"; therefore, any mate connectors on these parts will be at different angles as well.  

    Onshape allows you to create the wheel and the hub in the same part studio- if you do so, you can create the geometry defining the holes in the same sketch, and the parts will align correctly in the assembly.  Making multiple parts in one studio eases the burden of mating them in an assembly, since you can define their geometric relationship in the parts studio.  If this approach is unfamiliar, check out this tutorial on multi-part part studios.
  • steve_shubinsteve_shubin Member Posts: 630 ✭✭✭✭
    edited December 2021
    @jason_traud

    You could also EDIT the two existing fastened mates. As such, you would not need to change the location of these mates, but rather, just change the type of mate from fastened to revolute

    It’s a matter of what is called — degrees of freedom, that allows you to use two revolute mates to get the job done, with the mates kept in the existing positions

    The revolute mate will use the same centerpoint as the fastened mate, but it will give you an extra degree of freedom to rotate. But once you use two revolute mates in combination, that will stop any rotation. And then there is the fact that revolute mates act in a planar fashion. So that planar capability will keep the surface of part one flat against the outer wheel

    Changing one of the mates to a revolute mate and the other to a ball mate would also work

  • steve_shubinsteve_shubin Member Posts: 630 ✭✭✭✭
    edited January 1 Accepted Answer
    @jason_traud

    https://cad.onshape.com/documents/321ed8475949a7f47900000b/w/ac5227793cf45d2dc9dee6d4/e/fa4ab69832afad73b3f65eae

    In the assembly of this document,
    nothing is over constrained / defined

    I used the methods described in my above post

  • steve_shubinsteve_shubin Member Posts: 630 ✭✭✭✭
    edited January 1
    @jason_traud

    Being as the axle is set up to accept some set screws, I figured it was best to use fastened mates from the hub to the motor’s axle.  As a result, the wheel does not rotate, because the axle was never set up to rotate within the motor

    I figure the proper thing to do is to make it so that axle can rotate apart from the motor. But I figured that’s a modification to the motor and the axle that you could make, if you wanted to


  • steve_shubinsteve_shubin Member Posts: 630 ✭✭✭✭
    edited January 1 Accepted Answer
    @jason_traud

    https://cad.onshape.com/documents/1bd9296df4f454c918d7046a/w/431266ff0a04058136ae1a03/e/286b43d97366aeb0845fa4be

    I modified the motor — separated the axle from it and removed the end that had the wires

    Now you can animate the wheel also






  • jason_traudjason_traud Member Posts: 13
    @steve_shubin

    I folded your changes into my design and versioned the design. Thanks for the help!
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