Finding Nominals for SPC Ports without CAD

Question

Hi Guys, 
 What is the best way to find nominals for SPC ports if you don't have Fixture CAD? I know some people use Set Master Pins and take points but I am required to measure location of SPC ports. 
 Usually I have Fixture CAD but they changed the location/angle in which these ports come in to measure the trim edge and I can't seem to find a solution to measuring them accurately. 
 Any guidance would be appreciated. 
 Thanks

Matthew D. Hoedeman · Answer

I never use FIXTURE CAD to verify a fixture. By doing so, you are ASSUMING they designed the fixture correctly, and I've seen it many times where the fixture is either NOT made correctly, or made to the wrong revision of master product data. I only use master product data. 
 
 To do the SPC port, measure it as a cylinder and a plane (cylinder inside or on gage pins and the plane on the face). Intersect the cylinder and the plane for the first point. 
 Then create but do NOT measure a plane (using DCC features) on the part close to where the cylinder would intersect it. Then intersect the cylinder and that plane for the 2nd point. 
 Now, take the XYZ values for the 2nd point and using VECTOR point (DCC features), click on the part data where the point is, TYPE in the XYZ from the 2nd point and FIND that on the model. Create that point WITHOUT measuring, then 3D distance the vector point and the 1st point to get the distance. I did this all the time when "CMM DOESN'T MATCH THE FIXTURE" garbage to prove my numbers were correct and the fixture had issues. 
 
 I also only use master part data for checking anything else on the fixture, same reasons apply, master part data is master, not what someone did to make the fixture, simply use stock thickness to generate the points for the fixture check.