Parallelism

[[Re...]]

I have a question in regards to parallelism. I have typically use outer tangential evaluation on my planes for the calculation of parallelism. Should I be evaluating parallelism by both outer and inner evaluations for boundary when there is no modifier shown in the datum reference frame, or should I be evaluating only by least squared. Perhaps our prints need be updated with a "T" modifier to satisfy functionality? ASME Y14.5 - 2009 is the standard I need to satisfy. Any input would be appreciated - Thanks.

[[Ja...]]

I don't think changing your feature from LSQ to min feature or outer tangent will change your results. It is an evaluation of the features points, not the theoretical plane. The datum should be set to outer tangent. If there is an exception to that rule I have yet to run into it.

[[Ca...]]

Calypso automatically evaluates features used as datums with OTE, right??

[[Re...]]

Are you referring to Systems Methods - Outer Tangential Element - Ref. Calculation as per ISO 5459 - Then I would say yes

[[Ja...]]

I interpreted that as if you were evaluating a plane. If you are evaluating a cylinder then what you use for feature evaluation will make a difference because it is an evaluation of the cylinder axis.

[[Re...]]

Example - Measurement Methods in Settings - Outer Tangential Element with Ref. Calculation per ISO 5459.

When checking the parallelism of Plane1 to Datum A plane, I will get different results depending on feature evaluation settings.

If I have both planes set with the evaluation of Least Squared in the feature setting, I get a parallel measurement of 0.0152

When I have both planes set with the evaluation of Outer Tangential Element in the feature setting, I get a parallel measurement of 0.0154

When I have both planes set with the evaluation of Inner Tangential Element in the feature setting, I get a parallel measurement of 0.0148

Which method or methods combined, do I need to use to satisfy ASME Y14.5 -2009? Note there is no Tangent Plane Modifier on print.

[[Ja...]]

Sorry if my comments were confusing. I thought we were talking about perpendicularity. But still, if you don't change the evaluation settings of the datum and only change the evaluation settings of the feature, the results shouldn't change and the datum should always be on outer tangent per ASME.

[[Re...]]

Jason,
If I understand correctly, are you saying that my evaluation of the datum feature will always default to the "Measurement Methods in Settings - Outer Tangential Element with Ref. Calculation per ISO 5459" regardless of the feature evaluation setting? And that this setting satisfies ASME standard? However the reference feature can change with its evaluation setting. My question is what evaluation setting should the reference feature be set to? Thanks

[[Ja...]]

When I was talking about a feature and a datum, I was referring to within the parallelism characteristic there is a feature and a datum. The evaluation settings within the characteristic do not have to be the same as the feature in the feature list and yes the datum in the characteristic should default to outer tangent with the settings you have in measurement methods. You can change it but it should be on outer tangent. I'm not sure what you mean by reference feature. If you mean the feature in the feature list, then that shouldn't matter. I normally leave it at LSQ. Look at it as a collection of points and set the evaluation within the characteristic according to that particular characteristic.

[[Re...]]

Thanks Barry,
I still have the habit of setting a number of my evaluations through the feature rather than through the characteristic. Although through the characteristic makes more sense. Sounds like the feature "non-datum" for parallelism needs to be evaluated at LSQ either through the feature or characteristic setting to satisfy ASME std. Does anyone know if by setting the feature "non-datum" for parallelism to outer tangential gives what one would needed for a (T) modifier within a parallelism callout, or is this done by another method?