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DimXpert unpredictable and incorrect constraint status

Question asked by Ken Lux on Dec 13, 2019
Latest reply on May 4, 2020 by Marc Trumpi

Does anyone know or have any links to information on how DimXpert decides if a surface is unconstrained, underconstrained, constrained, or overconstrained? My experience is that the calculation it does is unpredictable and often incorrect.  Some examples:

  1. Often adding a single constraint to an under-constrained surface will make it over-constrained.
  2. Picture two holes on the top surface of a box with all of the sides constrained. Let the X-Y plane be the top of the box. Insert a +/- dimension for the x-distance of one hole from the closest side perpendicular to the x-axis. Insert another +/- dimension for the x-distance between the two holes. Now DimXpert reports both holes as overconstrained. Sometimes if you set the +/- dimension to be from the 2nd hole to its outer face, then things are OK even if there is a constraint on the total width.
  3. Sometimes you get a message saying "Added tolerance has overconstrained the part" when you add a datum.
  4. Adding a hole pattern on one face causes another face to go from fully constrained to underconstrained.
  5. Many, many, many times I end up with 1 item overconstrained and 1 item underconstrained.
  6. Sometimes Ctrl-Q or closing SW and re-opening it will resolve the 1-item-over-and-1-item-under problem mentioned above.
  7. There is zero documentation available outside of the help file that is little more than just a list of what the property managers do.


I would like to do a tolanalyst study, but I can't get DimXpert to constrain things properly.


I suspect that once you have a datum reference frame that when you add another datum, DimXpert lets the oldest datum float. If so, this is useless for any part that needs multiple DRFs.