Base alignment

[[Ga...]]

Is it wrong to create a base alignment using a plane, line in X & a line in Y and create an intersect point of a line in X and a line in Y for my origin? Will my features be slightly skewed?

Thanks

[[Da...]]

For a stable base alignment and your needs, it might be okay. If you use that base alignment for the evaluation, it's a different thing. A datum system according to ISO or ASME is not built with intersection points, but then again you would use more than just lines if you wanted best accordance to any standard.

For everyday use, using a plane and two intersecting lines could be enough, but it's not a functional datum system.

[[Ga...]]

Perfect! Thank you for that!

Maybe you can tell me why some of my diameters, in the same plan, show the diameter trihedron skewed while other diameters, in the same plane, match the alignment?

[[Da...]]

Are you measuring off of a CAD model? Are your diameters measured as cylinders or circles?

[[Ga...]]

Not off CAD model and measuring as circles. Is there a way to correct this and will my measurements be off?

Thanks,
Gary

[[Da...]]

I suspect your nominals might be off. A skewed circle might have angles not perpendicular to your workplane.

Check your nominals and make sure they are right!

[[Al...]]

If you are not programming off a CAD model, or even if you are and using "Define Points" on a CAD model to create your features, you should verify that any feature nominals are what is expected per the print.

Regardless if you are scanning or collecting single points. Another option is to project the circle to a measured surface.

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[[To...]]

Something does look right. I don't know that I have seen a circle measured on a part ever have projection angles other than zero as circle's axis always snaps to closest primary angle. Even if points were not taken at same depth.

[[Ga...]]

Thank you very much for the information. I am not programming off of CAD jut taking points and setting the nominal. I have looked and the reason is because my nominal we not correct. Thanks for straightening me out with that, I appreciate it.

Gary

[[Ga...]]

Thank you very much for the help. On another note, I keep getting these showing up while i am manually programming. Mostly I get them when I used the F11 center hole shortcut. Is there a way to get this to stop?

[[Da...]]

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I see an XXT plate in the picture.
I was surprised when started to program tactile on O-Inspect that Base Alignment doesn't work if point feature used for clocking isn't touch point evaluation.
Might be something you could check.

[[Ma...]]

Allows remember that when using a Cylinder as a Datum you must pay attention to the form of the cylinder. I always use 3 to 5 circles in a bore, when it is a datum, and recall a 3D Line through the center of the cylinder. Do just limit it to 2 circles because just one of the 2 circles is not right the whole 3D line is off. I've included a pdf from The CMM Handbook about cylinders.

[[Je...]]

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Minimum advised ratio for a cylinder datum feature is length:bore ratio of 3:1 or greater as indicated in the ZEISS Cookbook series. Application of the proper evaluation method is critical for ASME vs ISO (outer tangential vs LSQ, measured feature axis vs extracted derived feature etc)

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It also appears from your provided screenshots that you have "Rounding" enabled. This can very easily appear as if you corrected your nominals after feature creation as the values will be rounded. Please ensure your setting is appropriate to your needs.

[[Lu...]]

https://portal.zeiss.com/knowledge-base?id=1168226