Jump to content

Unequally disposed tolerance zone - GOM computations


Recommended Posts

Hello GOM users!

i was wondering if somebody was strugling with the way how the GOM computes the Unequally diposed tolerance zone Actaul value?

I have this DWG callout of unequally disposed tolerance zone - Profile .020 AB (inches) unequally disposed towrads + TOL, so the Check values should be green for the tolerance .000 up to .020.

When inspecting in gom and using Unequally disposed tolerance zone i use following set-up:


and the results is .0471 Actaul - over TOL. As can be seen i am pre-setting the Unequally disposed tolerance in LEGEND - GEEN from .000 to .020, else OUT.


When checking for MIN and MAX it suppose to be the MAX value used for representing the ACTUAL value, right? So the results should be .0336, which is OVER .0136, but  GOM says .0471.


Can you help me understand the logic behind this GOM function?


GOM fan




Link to comment
Share on other sites


please have an look to the display properties. There can you find what influences the tolerance values:


Note: This is a new feature for the GOM Software 2021, in previous version only deviations to nominal was available.

According to your screenshots I would assume that you have choose to display the deviation values to the CAD. If you like to display the deviation values to center of the shifted tolerance zone you have to choose the other option.

And as always the actual value is smallest tolerance value so that all points are lie inside the tolerance zone. These tolerance zone is symmetric about 0.01 in over the CAD. If you sub this value from the max deviation picker you get 0.0236 (Note: This is only true if you choose ASME computation; for the ISO case some border effects can result to some different results). That means the maximum points are 0.0236 from the new defined center away and because the tolerance zone has been symmetric around the new center actual values is 0.0236 * 2 = 0.0472 (and the difference between the displayed error is simply a rounding issue, i.e. if changing the number of digits this rounding error will disappear).


Hope this helps,

Christoph Schult


Link to comment
Share on other sites


  • Create New...