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Constraints: How do I figure out what's missing?

I'm very much a n00b to CAD and to Onshape, but I'm learning... slowly.  I've got this shape that I'm working on... http://bit.ly/2dl7NU8.  It's under constrained, but I can't figure out what constraint(s) are missing to get it to being fully constrained.  Anyone?  In the larger scheme, is there a process that you use to figure out what constraints are missing or unnecessary?

Thanks,
Rob

Best Answer

Answers

  • brian_bradybrian_brady Member, Developers Posts: 373 EDU
    Your document needs to have copy permission so we can interrogate the sketch and see the dimensions and constraints.
  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 565
    Usually I grab the blue lines and drag them around to see what degree of freedom I am missing.

    Because your document is a link, I don't have access to the sketch so I can't tell 100% certain what the issues are.  But it looks like your curves on the outside of the nut don't have tangent constraints giving a sharp on them. It also looks like you have a point that is off-center which might mean your sketch isn't grounded to some external geometry like the origin.  I would double check that the center of all your circles are concentric/coincident with the origin and that all of your curves on the outside are equal and tangent.  Then all that should be needed is to dimension the size of the circles and arcs.
    Jake Ramsley

    Director of Quality Engineering              onshape.com
  • robert_wells594robert_wells594 Member Posts: 7
    Your document needs to have copy permission so we can interrogate the sketch and see the dimensions and constraints.
    Done.  See... n00b. Sorry.  The document is now public.  In the future, should I post a link like this (http://bit.ly/2dl7NU8) or is there a way to link my forum post to the workspace?
  • robert_wells594robert_wells594 Member Posts: 7
    Jake,

    Thanks!  I really appreciate the help!  

    I feel really bad clicking that it didn't answer my question, since you were so complete and helpful.  I'm just a little slow and still need some help :).  I tried to follow your instructions and while I think it's a lot better now (I was wondering how to fix the weird angles where the half circles met... thank you!), I seem to have done, or not done something that made it still unconstrained. Sorry for being dense.  I'm learning a lot here, so I really appreciate the suggestions!  Here's a link to the workspace (http://bit.ly/2cCOrOj)

    Trying to sus it out a bit, I was clicking on blue lines and trying to move them about.  I notice that I can move it as shown below by clicking on the point shown, but I'm not sure how to resolve.



    Thanks!


  • robert_wells594robert_wells594 Member Posts: 7
    You're awesome Jake.  Thank you!
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