same feature, different stylus, different value

[[Y....]]

Using Zeiss VAST XXT, with all stylus qualified.

I use stylus A #1 to create a z+ plane and make it z origin, and then I use stylus B #3 to measure the same plane, but z becomes maybe 0.03 or 0.05 anyway different from the plane create with stylus A #1.

What reason may cause this situation? (all stylus qualified)

Thank you for answering.

[[Da...]]

There are a lot of potential sources of error:

Are you using the same scan path/point density/speed? Ball size? Filter/outlier settings? Evaluation settings?

What is the feature form like?

Are you using RDS/CAA? What are your probe qualification sigma for the two probes?

If you measure the reference sphere with the two probes, do you get the same results? Do those results repeat? Just because it is qualified, doesn't mean it is going to give good results.

[[Ke...]]

You said: "I use stylus A #1 to create a z+ plane and make it z origin, and then I use stylus B #3 to measure the same plane"

Did you actually measure the plane with A #1, or did you just create it?

Feature form & measurement speed may play a role. How fast are you scanning?

Also: "z becomes maybe 0.03 or 0.05 anyway different from the plane create with stylus A #1" - different in which direction? If you are measuring it using LSQ, and the Base Alignment is using Outer Tangential as the default, it could be the difference between these settings.

As a "sanity check" scan the same plane 2x. For each (one using stylus A, and the other using stylus B), recall the plane into a single point (this will be the average of all the scanned points), and use the stylus A point as your Base Alignment Z value, and report the stylus B point for the second Plane, and see if the results are closer.

[[Wo...]]

easy way to check if your stylii are correct qualified is to use probe_1 and measure the ref.sphere. base alignment done by using ref.sphere. then measure the ref.sphere with probe_2 again. check xyz-coordinate. must be close to zero.