How to control the direction of line profile vectors

[[Kr...]]

Hello,

I am trying to measure various segments of line profiles, and I am having issues with the direction of the deviation vectors. 

To start, I created a curve. I've tried several techniques. the technique below was using the "construct" -> "curve" -> "edge curve" command:

Next, I selected a measuring principle. I used the "project curve onto actual" selection.

I then selected line profile and selected the DRF for the measurement:

 

The value shown for deviation does not match what I observed using the "inspection section on CAD" feature. when I turn on vectors I see that they are pointing along the face instead of perpendicular to the face. How do I toggle the direction so that it know to check the profile perpendicular to the face? See my issue below:

 

Thanks

[[Be...]]

Hi,

you have to understand the different semantics of the curve inspections:

• The GD&T line profile tries to identify the "smallest tube" around the nominal curve where all points of the actual curve are inside of this "tube"
  • We offer e-learnings for the meaning of GD&T dimensional evaluations 😉 
• The Inspection Section calculates the deviation in normal direction in the specified plane (normals of the curve are forced into the definition plane)
• Create Checks on a nominal curve which is linked via measuring principle to an actual curve (your example): e.g. create a check in normal direction (dN)

Hope this helps?!

Regards,

Bernd

[[Kr...]]

Thanks for the response, Bernd.

I found the "check in normal direction" command and was able to view results that way.

I just now noticed that it is automatically adding the diameter modifier to the GD&T callout. Is there a way to remove that modifier? Profile of a line is frequently, and I believe correctly, used to examine surfaces at specific cross sections. A quick google search yields the example below which appears to be consistent with how it is used in this part: Profile of a Line | GD&T Basics (gdandtbasics.com)

Thanks,

Kristian

[[Ch...]]

Small note regarding the diameter modifier: The software automatically detect if you using a curve or a section and display the diameter symbol if you are using curve data. Reason for this is that on curve it is not ensured that the data lies on a common plane. A line profile is possible for such cases, too. But the computation mode is slightly different and this difference has to been indicated with an diameter symbol (see ISO 1101:2017 for more details). If you are using a real cross section no diameter mode is displayed and the computation is done in this cross section, strictly.

[[Ch...]]

Additional note: The images that you have post are from the ASME standard. This standard doesn't know a line profile on a curve (at least to our knowledge). Therefore we have two possibilities:

 
a) to forbid such an evaluation

b) or to do same thing as the ISO

 

Due it is no harm (we are not in contradiction to the standard, we are simple provide a solution to a case that is not specified) we are doing the latter one.

[[Kr...]]

Thanks for the clarification.

I attempted to create the curve using the "construct" -> "single section" function and then  "actual section" for measuring principle. I was able to create a line profile in that section with vectors in the correct orientation, but every time I use this measuring principle, the end point vector messes up and destroys the whole profile reading:

 

Also, when using the line profile dialogue box, it allows me to select the datum system for evaluating the profile. As I toggle through datum alignments of the part at the top right of the screen, however, the "actual"  value of the profile changes with each alignment. I wouldn't think the alignment would affect those values, as I already selected which datum system to use for that measurement.

Does the part need to be aligned to the datum system being used for each measurement I want to view? does the datum system selection in the line profile setup affect the measurement at all, or is it just for the "label"?

[[Be...]]

Hi,

for concrete data analyzes you need to contact your local GOM partner and you have to supply the data!

You have to distinct how you create your actual section and how the check is evaluated (and which alignment or which datum system is used for the evaluation of the check). These are concepts which are trained in our training session. I would suggest you should contact your local GOM partner for training.

Regards,

Bernd