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Ref. Plane failure when parallel+coincident_to_line = coincident

Question asked by Tom Gagnon on Aug 28, 2017

I have a reference plane which I use for a Split feature, and it is defined as parallel to Front Plane and coincident to a line in a 'Layout Sketch'. When the layout sketch is altered so that the line is dimensionally coincident to the front plane, then the Plane reference geometry fails even though it is conceptually true. (Image Broken) The plane failing means that the split also fails to update correctly. The Split is intended to be flexible per use by adjusting the 'Layout Sketch', but in this case, must be redefined as coincident to endpoint of that line instead of coincident to that line (image Repaired).


(Context, 3rd) Image reference: I'm speaking of SplitPlane2, which is now shown as suppressed because of its failure.

This is a complex weldment part which is used similarly among different applications within this very large multi-site project. Very simply, it consists of C8 channel with 3/16" diamond deck welded to its top. The deck is a single (30' x 9'-4" x 3/16") extruded solid from the top surface, and then Split into sections 8' or less to express what materials we can acquire to fabricate this. The 'Layout Sketch' is used to place the interior stringer channels along its midpoint, as well as the Split Planes for the decking, so that the deck seam is equally supported on each side by the channel below. When I started adjusting the locations of the lines in 'Layout Sketch', as soon as the line which helps define SplitPlane2 became coincident with the Front Plane, it failed, which cascaded to the Split feature which uses it.


Lesson learned: For a reference plane, parallel to plane and coincident to point is more robust than parallel to plane and coincident to parallel line.

It is an admittedly minor issue, because it can be worked around by changing the constraints. All the same, the design logic must be adapted to failures in the software, even when otherwise geometrically consistent and valid. It ought to work better. One and Two.



1. Is this problem still present in 2017? I'm running 2016 SP3.

2. If this isn't fixed with 2017 and beyond, is it worth submitting an SPR for it (or is there already one for this issue)?