Nominal+Actuals not equaling PiWeb

[[De...]]

Hello all,

Today I've come across my first real issue with data collection. Attached I have two screen captures, one of the Feature and the other being Characteristic measurements of the same hole on a part.

In the Feature tab, the Nominal and Actual numbers are right where they're supposed to be according to the print. In the Characteristic tab as a True Position with the correct Nominals, it's saying that the hole is way off. I've never had anything like this happen before and I'm curious if anyone knows why it's like this and what I should do.

When measured on another CMM, everything is correct and well within tolerance. Any and all help is truly appreciated.

Here are the Feature Nominal and Actual measurements:
Here is the Characteristic Position:


I've tried:
Measuring this hole as a cylinder and circle
Different probe tips
Projecting everything to the same plane
Completely starting over twice

Everything yields the same result. Any ideas on what to try next?

Thank you for your time.

[[Ri...]]

You should re-check all of your nominals because your Cylinder Datum C is showing a nominal tilt in respect to the Base Alignment in the A1/A2. If Datum C is supposed to be Perpendicular to A, then the A1 and A2 should be 0. I would also suggest checking Datum B as well then.

In addition, the Nominal and Actual values via the Features tab is at the Feature Coordinate Center. On a 2d feature like a point or a circle this wouldn't matter, but on a 3d feature like a Cylinder it is at either the top or bottom of the cylinder surface; on a Plane it is one of the corners. So having said that, the actual values for the X,Y, and Z are meaningless.

[[Ke...]]

(Always) check the form on all of your Datum Features.

[[Ri...]]

See attached image.

Capture.PNG

[[De...]]

Thank you all for the advice on zeroing the A1/A2.

I did that and the True Position instantly came right in with much better numbers. I've had problems with the A1/A2 before but never to this extent. Truly a piece of information I'll remember to check from here on.

Attached is the revised numbers and output. Thank you all again for the helpful knowledge!