Your opinion, please

[[To...]]

I have my thoughts on what is going on with this circle, but I'd like to hear what you all think.

[[Ch...]]

i've seen this once or twice before, I think I recall it was a hole and something was causing probe to shank, or it was really out of round ,etc.

[[Ja...]]

I suspect similar to Chris - probe shanking out, an out of round hole or a burr, or a combination of all three.

[[Ke...]]

I see this a lot, when I am measuring a small internal diameter with a "not small enough" stylus. 

e.g.: inspecting a 4mm dia hole with a 3mm stylus. After I use a 2mm or 1.5mm stylus, the geometery looks good; but the values are no different than the larger stylus

Edited yesterday at 03:16 PM

[[To...]]

The thing that puzzles me is the low form value. 

[[Du...]]

Do you have Magnification for the feature on?

[[Ch...]]

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I'm with you, what's up with the good form value?  Looks heavily filtered.  I'd look at the unfiltered data and check difference been min circumscribed and max inscribed. 

[[To...]]

No mag. No filters or outliers. Not sure why scanning 750 degrees. LSQ. Haven’t checked mask settings. 

Edited yesterday at 03:50 PM

[[Ch...]]

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something is masking out points.  its set to 1048 points but only 462 are used for the evaluation.  

 

[[Ke...]]

Try taking discrete points... maybe a dozen or so?

[[Pe...]]

I've seen calypso make some pretty funny shapes when a hole is so far from where it should be.  Looking at your X and Z.

[[Mi...]]

Is there a loose/damaged component? The low form error is confusing, though. Does it have something to do with the fact that it's labeled a cylinder but has the circle symbol in the feature window? Seems like there was some tinkering with that feature at some point. I agree with the previous replies about shanking and burrs but I'd think the form error would be higher, even with filtering. I've seen something similar to that caused by a cracked (off brand) carbon fiber extension. The crack was causing the extension to flex more one way than the other and the result was similar to what you have pictured.

Edited yesterday at 07:49 PM
More information

[[Tr...]]

Had this happen when the hole is small, relative to probe, and out of expected position.

[[To...]]

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 I remember many years ago that masking was tied solely to the first .25 seconds of the beginning of a scan, and it still is when scanning less than 360°. So, when you scanned 380° on a circle, the masked points might only be a portion of the 20° over-scan relative to the scanning speed.  Then, Calypso changed to masking whatever the over-scan amount was.  My assumption is that even though they are scanning 750°, the resulting circle is only using the data from the last 360° of the scan.

[[To...]]

For a little more detail, the basic shape is a cube with many same-sized holes machined parallel to axes created from opposite corners of the cube.  All of these holes exhibit the same odd shaped data set.  With the exception of the good form, I believe the stylus is shanking.  These results lead me to believe there is either an issue during the machining or the base alignment.  The measurement plan is from the customer and the results from a part they machined on their machine.  I just need to be sure before I tell the customer. 

Edited 8 hours ago

[[Ri...]]

Are you using an L shaped probe?