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Equation driven curve

gisele_macedogisele_macedo Member Posts: 2
I am trying to draw a curve using this feature (https://cad.onshape.com/documents/578ff8b3e4b0e65410fcfda3/w/d33395f174e5b38f4abd6097/e/0c17de6a800d4aed83de417f) I already tried in several ways, but always get "invalid expression" Can someone help me with that?


  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 4,228
    Director, Technical Services, EMEAI
  • mahirmahir Member, Developers Posts: 1,204 ✭✭✭✭✭
    edited May 24
    Hi @gisele_macedo. I can’t be sure what is causing your specific error without seeing your document. However, the issue is often inconsistent application of units. For this particular example, set X = #t mm. You can multiply by whatever scaling factor you want that corresponds to the max value of X you need. Use X = #t-.5 if you want your curve centered about x=0. Type in your formula for Y but include the value of theta inline, not as a separate formula. Make sure units are consistent. X Y Z need to evaluate to length units. Trig functions should have an angle as input (either deg or radians). 
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