find nominals from CAD

Can anyone tell me why my actual and theo vectors are reversed when I use find nominals from cad when making manual measurments? Theo XYZ is correct but actuals are wrong because probe comps in the opposite direction. Driving me nuts....I'm sure it's something simple, just haven't figured it out yet. Works most of the time and my models are good.

PCDMIS Portable 2011 MR1

I can think of two reasons that's happening:

1) you're pulling nominals from the right surface, but they are incorrect-- aka there's a problem with your model. PCDMIS can sometimes flip a surface during CAD model translation, resulting in a situation like yours. After we import and before we align, we should always "heal" our model.

Edit > Graphic display window > cad vectors.

Left click box select the entire model and then "fix selected surfaces".

When you press apply, you should see some of the green surface vectors reorient themselves. Now your FindNoms will pull the fixed nominals from the healed model.




2). You are might actuall be pulling your nominals from the other side of the model!! I've seen CAD guys make a double sides surface with no space between the sides, and DMIS ends up pulling the wrong IJK and right XYZ. Massaging your FindNoms tolerance in Setup might help, but I think it's easier to just program the part offline, especially if you have a model, and execute at the end.

Of course, this doesn't help us with manual scans, but AEs have many Jedi tricks. Let me know if these work.

From the road,
Colin Simithraaratchy
Colin.simithraaratchy AT hexagonmetrology.com

If there are just a few surfaces like this, you could try using the "Flip Vector" button in the feature creation dialog box.
I have had a few models where just a few of the surfaces were messed up in this way and flipping the vectors worked for me.

Seams odd, but I will give it a try. When I program offline to the model everything looks good.
Thanks