Why isn't the coincident constraint working right?

Answers

• martin_kopplow Member Posts: 1,288 PRO

  February 23

  I can't reproduce. Works for me.

  • Is this a curve resolution issue?
  • Mind sharing the file?

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• BKL Member Posts: 4 ✭

  February 23

  https://cad.onshape.com/documents/405fc6ccf1dd5016f8f94d01/w/01027517f96061458abaf55d/e/f4c89a67141ec9f5d2fec226?renderMode=0&uiState=699ccba300c12c298a3f1cae
  Its in the sketch I renamed to "problem child"

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• martin_kopplow Member Posts: 1,288 PRO

  February 24

  Okay, here we go, trust me - I'm a pilot.

  I thinks we see different issues here happening at the same time:

  1. You have generally redundant vertical and horizontal constraints (two within the sketch, one to a point in sketch 3), driving the sketch to the edge of overconstraination.
  2. You constrained the lower spline handle to the spline itself, then dimensioned it to be very close to the construction line endpoint. That does work, but may put high tension on the spline for downstream edits (I changed that to an angular constraint to play with in my sample).
  3. You zoomed in so far that the limited curve screen display resolution made the point appear off the curve you constrained it to.

  Then you probably tried to work with the sketch and ran into some limit and assumed it was because of the point being off the curve, but I suspect the real issue to be one of the others, or yet another one, unknown at this point in time.

  Try if your problem persists with this document. I did not touch the coincident constraint in question.

  I replaced the first constraint to sketch 3 by a "use" of that point you wanted, and deleted the horizontal constraint on the outside end point of the construction line while keeping only the horiz. constr. on the construction line. There seem to be loads of inter-sketch horizontal and verical constraints in your model. These may work on an individual basis, but the more sketches are involved, this method bears an increaring risk of creating a circular reference at some point, or breaking one sketch by editing another. Not sure if it already happened here, though.

  Also, why do you build both sides of that car by mirroring the curves that surface them? Why not fisish one half and the mirror the body panels? You're right, this may well be the most inefficient way to design a car body, but we all have to start somewhere, don't we? ;0)

  I recommend going through the surface modeling lessons in the learning section. It is all covered there in great detail there.

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