Probe Qualifications

[[To...]]

I recently encountered a seasoned Calypso user with a routine that I have never heard of before. When he creates a program for qualifying his stylus systems, he has a Probing Qualification object which performs the default qualification routine, either Passive or Tensor, depending on the sensor type. Then, he adds a second Probing Qualification object set to Geometry Qualification. He swears that his qualification results are significantly better (no data to back it up).

I suppose this might be worth while after a Tensor qualification but seems to be a redundant action after a Passive qualification, as it performs the geometry qualification it at the end of the routine.

Does anyone else do this?

[[Mi...]]

On XXT we do often see an improvement in the S value if we immediately do a Geometry Requalification after the Passive, Can't explain why, and very rarely do we actually bother to do it.

Since we don't actually KNOW what's happening behind the scenes with each method I always theorized that doing the Geometry Requal after was better because it used the new calculated sphere location instead of basing it on your initial probing and the first few points that happen during a Passive qual.

Quite reliably I will struggle to get an S value under our limit on XXT, then without changing anything just do a Geometry Requal on the same probe and it comes out great. Biased thought on my part? maybe.

[[No...]]

Isn't the S value the standard deviation calculated from all points taken? Assumption: the probability of getting a smaller S value may be higher with fewer points taken (geometry) than with a higher number of points (passive/tensor). Of course it depends on the actual stylus.

[[Da...]]

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I can't see it different. The more the points, the greater the sigma.

But want to be sure, on passive, the sigma is to be from the last 6 points, right?

[[To...]]

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That is my understanding.

[[Da...]]

Maybe I'm missing something. When you say better sigma #'s, how much are we actually talking about here? What are your average readings?

[[Mi...]]

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I've always been told it's from the last 6 points too, but with how often the Geometry Requalification gets significantly better numbers I am doubting that.

In general, we limit our XXT machines to 0.001 sigma, in reality they are almost always in the 0.0004 to 0.0006 range. At times when the Passive mode is sitting above 0.001, I've tried the Geometry Requalification and got back to the normal range.

Now yes, that likely means dirt, or damage in some way that needs investigating but to me it heavily indicates that the S value is coming from more than the last 6 points of a Passive Qualification.