Datum Targets

[[De...]]

Hello,

   I am looking to limit the area on a plane to only the datum target area (example from the attached print). Can you let me know how to limit the "fitting element" or to create a new nominal or actual plane which only selects elements in the datum target area?

   Thanks.363BB863-69F7-4BF1-A4A8-A2ACE94BECB6.SNAG

[[Ma...]]

I can't open snag file. Post a jpg or PNG photo.

[[Ch...]]

Preferable you have a patch on the CAD that describes the datum target (or you are able to create such one). Then you can simple use select patch on the nominal and the measuring principle fitting element with restrict selection to nominal.

Otherwise selection by geometric contour could be a good starting point. As Marco Giraudo said we can not see your images but I am assume that the area is something like a circle. Then you have to create a nominal circle (e.g. Circle by by point and normal) and use the mentioned selection command. Afterwards you can use the measuring fitting element again.

Note: To get a good result the mesh/cad triangulation should fine enough to  allow a good representation of your form.

[[De...]]

Hello Marco and Christoph,

   Thank-you for the prompt replies and explanation.  I have attached a .jpg below to help clarify.  Yes, it is a circle datum target that I am looking to localize the datum to.  It is on a larger flat plane so I want to select just the area in the datum target.  I may be able to add the feature to CAD, but if it is possible to do in the GOM software directly that would be preferred,

   Thanks,

 

[[Ma...]]

I think you can do a fitting plane selecting only the area you want and then measure it with the referenced costruction. See the example below.

[[Na...]]

Hello, 

as Christoph proposed, selection by geometric contour would be a better selection tool in this case. The radius can be exactly defined by the element you are using for the selection:
https://techguide.gom.com/en/article/cmd_selection3d_select_by_geometry_contour.html

With a "ring" as the selection like in your drawing, a cylinder or circle may be suitable for the selection. 

Regards,
Nanno

[[Ji...]]

For circular datum target elements, a choice would be to use a touch point disc that represents the size of you datum target.  This will touch the high points of your datum target areas which will simulate a hard gage.

[[Ch...]]

From a practical point of view this may sufficient to solve your inspection problem. But it is not what is mentioned on the technical drawing.

First datum target as used in the technical drawing describing an area instead a single point, i.e. the resulting datum is a plane not a single point. Of course you can argument that a plane could be computed from the point using the touching direction.

Second to establish your datum point you are using a non-specified direction (the touching direction) and I would assume you are using the same unspecified direction to estimate a plane from the touching point.

Therefore the usage of a selected area instead of a touching disc is to prefer to get reproducible results.