Calibrating Star Probe Problem

[[Za...]]

Hi everyone,

I need to qualify star probe to measure some kind of holes. My problem is Ref. Sphere diameter is 30 mm and star probe length is 10 mm from the center. Because of that, whenever i try to qualify my star probe it is starting to do sphere thing then prob shaft touches to the sphere. And calibration is giving alarm.

Is there any possible way to fix this? What else i can do?

Thanks all.

[[Ri...]]

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If this is an active head (VAST, VAST XTR, VAST XT) you can reduce the sphere coverage from 180. If this is an XXT, you can reduce the sphere coverage, but it will still do the "death spiral" scans at 180.

[[Cl...]]

Because of the large variety of stylus size/length I was forced to get a second reference sphere (8MM)

[[Za...]]

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Thanks for your answer.

We are using VAST - XXT. So if i reduce the sphere coverage, it won't go 15 mm from the top point.(D = 30mm) Theorically shaft will not touch the sphere will it?

[[Ri...]]

It will on the XXT.

The XXT qualifies in two steps - the first step is a scanning of the reference sphere for the bending parameters (6 passes, 3 down, 3 up). The second step is either a 5/6 single point measurement (3/4 around the equator, and two at the top of the sphere).

If you reduce the sphere coverage below 180 on an XXT, it will still scan 180 degrees for the bending parameters. The only thing it will reduce is the sphere coverage for the 5/6 single point measurement. Most likely it will still shank during the bending parameters generating erroneous data.

[[Za...]]

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What if i manipulate Rep. sphere dimater as "12mm" ? Would it work?

[[To...]]

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No.

[[Mi...]]

All you need to do is buy a smaller calibration tool. We have an 8 mm & a 29.96mm calibration sphere

[[Ma...]]

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I have had this problem in the past with an XXT head. Not sure if there are other solutions but I was able to use a 10mm probe and also an 8mm sphere.

The reason the 10mm probe was used as a reference sphere is essentially, my company was cheap and didn't want to pay for it. Although it's taboo, you can use the 10mm probe especially if it isn't used. Just have a fixture to hold it high enough up that the xxt won't crash into the granite/plate.

If the company doesn't mind spending the money, buy the sphere and just replace your standard 30mm one with it if you don't buy the stand for it.