Probing Dynamic at 1%

[[To...]]

I recently visited a high tech aerospace customer with a Contura with a VAST-XT Gold and another Contura with VAST-XTR. When they qualify their stylus systems, they insist on using 1% probing dynamic. They have done extensive testing and claim they do not get the accuracy they're looking for if they use anything above that. Of course, probe qualifications are an "all day" event.

I'm curious of what everyone thinks.

[[Is...]]

maybe the quality of their stylus system is not good enough..

[[Ri...]]

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I would agree that a lower probing dynamic will tend to increase the repeatability and thus the accuracy of the positioning.

There is a reason why we always suggest a maximum of 30% on mechanical driven machines (DuraMax, O-Inspect, etc.). With large styli, and large surfaces it isn't as noticeable, but as the surface and the styli gets smaller, the more noticeable this becomes. This is also compounded with the behavior of the XXT (reacting to the surface instead of pushing against the surface).

On air-bearing machines this typically isn't needed because air driven machines tend to have much better repeatability and thus much better accuracy of the positioning.

Now as your styli/stylus system becomes less and less rigid, I would suggest to turn this down.

I am sure that if someone performed a study, they would see the differences in measuring, but at some point you would get diminishing results.

Having said all of that, 1% seems so extreme. I've only ever done that a few times, but it was trying to hit a tiny surface with a tiny probe. Worked well.

[[To...]]

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I have never heard of this, nor have I seen a need to do this. Is this an official stance by Zeiss? I've only ever used 30% on 0.5 and 0.3 styli to reduce breakage.

[[Da...]]

We use 100nM probe force and 50% dynamic on all of our probes and calibration. We run Very close tolerance, and this works best for us. But we also run our parts at the same settings as the calibration. I wonder if they are doing this. 1% would take forever!!!

[[Ri...]]

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Nope - they actually frown against us teaching this, but we have plenty of first hand experience with this.