RDS-CAA Angle Discrepancy

[[De...]]

Hello all,

 

It has recently come to my attention that I am getting different measurements while using different angles on my RDS-CAA head.  Checking a 2.49969 Ring in the same spot with A+B at 0° it's perfect.  Then using B at 35° and again at 45° in the same locations yields different results.  I am using the 35° method to ID grooves in customer parts that have ±0.001 tolerance.  This is right after requalifying the probe being used as well.  With this much of a discrepancy from straight to angled, I'm wondering if I need to try a disc probe and stop using the articulation of the RDS head.

 

Any suggestions or ideas on what I could/should try to make this better or is it "Go with a disc" at this point?

 

Attached is a PDF of the 35°, 45°, and straight scans.  The screen capture is of how I am doing the scans for the angled measurements.  For the X axis measurements I have "A" at 0° with "B" at -35° and 35° while for the Y axis "A" is turned to 90° and then "B" repeats the -35° and 35° angles.

7-27-26 35-45 DEG CHECK.pdf