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How to analyse color scale, maximum and minimum deviation label for a position ?


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Hello dear GOM user,

First of all, as this is my first post, i would like to thank everyone for the variety and quantity of the information shared !

When i create a position/location of a plane i'm interested in interpretation of the color scale and labels.

First i create my datum system, X+ is going to the right, Y+ up :

image.thumb.jpeg.b19314f40617a7b6c9b7bc500b789e1a.jpeg

Same datum system but zoom out view, X+ is still going to the right and Y+ up :
(You can notice the locating plane at the bottom of the sample)

image.thumb.jpeg.021c12e6a34d51400097f2eafed56d8b.jpeg

My misunderstanding can be found in the next capture. In this view X+ is going right and Y+ is going down
The mesh (in grey) and the 3D model (in transparent blue) are align with the same datum system, the one i will use to calculate the location of these 2 planes ("Plan 4.025 X" and "Plan 4.025 Y")

For the "Plan 4.025 X" my max and min label are +0.153 and +0.117 but we can clearly see that the X measured dimension of the real plane is shorter than the nominal, which doesn't make sens to me
On the contrary, for the "Plan 4.025 Y" my max and min label are +0.07 and +0.015 and we can see that the Y measured dimension is longer than the nominal, which make sense
 

image.thumb.jpeg.c3373fd2271f8405e44025fd6a008f0c.jpeg

 

Can someone plz explain to us why the min and max labels are positive in the case of the "Plan 4.025 X" location ?

Thank you very much in advance !
 

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I had also the same problem. It´a problem of GOM Software. If you use surface profile you get the correct colors.
I use a workaround: I create a datum system that is rotated 180° for my critical position check. I choose the name identical to the normal reference system and ends with a "."
When creating the datum system you can enter a rotation.

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Hello,

this behaviour is due to the fact that the direction of the position tolerance is not derived from the normal vector of the plane but from the orientation (or the positive/negative direction) of the datum system. This also affects the coloured deviation visualisation and the deviation flags. As

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has already described, it makes more sense to use the surface profile instead of the position for integral geometry elements (such as surfaces, lateral surfaces, etc.). The surface profile uses the normal vector of the element.

We know that this behaviour can cause confusion for some customers. There is already a corresponding feature-request. I have already attached this forum entry to the issue.

I hope this helps for now.

Greetings, Lukas

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Deviations are using "Sigma" so right-click on the deviation to edit then change it to "all points".

Perhaps is better if you use a Profile (with a surface patch).

 

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