I see this has now devolved into the religious war over shown and created dimension.
Here’s my take on this.
There are many times where the design intent does not match what’s required on a drawing. Redefining the part just so you can get the dimension you want on the drawing can ruin the built in design intent of how it was modeled.
I’ve received parts that have almost no dimensions, because the engineer referenced features of the mating parts in the assembly. In that case, I’m not going to redefine his part just so I can show some dimensions.
In another case, we had a sub-assy that needed to show the range of motion. The skeleton drove the placement of the parts, but we needed to make weldment drawings that didn’t match the assembly structure. If we had tried to make assemblies that matched the drawings we needed the motion component of the design would not have worked. We made simplified reps and family tables to create the various weldment drawings.
There is no hard and fast rule. You do what you need to do to get the stuff out the door.
I use shown dimensions when I can, but I have no problem using created dimensions either. There’s no need to put Galileo on trial again over where the center of the universe is.
David Haigh
Phone: 925-424-3931
Fax: 925-423-7496
Lawrence Livermore National Lab
7000 East Ave, L-362
Livermore, CA 94550
________________________________