Doubts about how is calculated GD&T parallelism

[[Ru...]]

Hello

 I was checking the GD&T parallelism of a plane against a Datum D, and when I get the maximum and minimum labels it’s a strange information   

 For minimum label shows (-0,397) that match with colour map, but the value for maximum label (+0,397) doesn’t corresponds with colour map :In other pieces  

Obviously the parallelism m is the range between maxim and minimum value, and as both are the same, in first example below these means 0,397 + 0,397 = 0,794

And I see the same issue in other parts: the maximum and minimum value is always these absolute value, just changing the + or –  seymbol  …. an sound very strange th always the min and max value are the same value in all pieces ,  I dont  belive it 

  I think that  something is missing for me to get  this max/min labels

 

 

[[Ma...]]

It is representing plane in mid position so you see both numbers the same. It's just visualisation.

Software can not tell if you want to see only 0 and +deviation or -deviation and 0 - so it's placing to middle of deviation to show color map.

[[Ru...]]

Thanks Martin

 But the logical way for a clear understanding for a parallelism value 0,794 is get a maximum label = 0,251(as example) and as minimum the label -0,543 (as example) so the range = l0,251l +l0,543l = 0,794

So with that information we can see where and how much material we need to add or delete on each area to get a correct parallelism

 

And I see the same behaviour for flatness of a plane, where the maximum and minim values indicated in labels are the same values ALWAYS so we cannot know how much material we need to add or to delete to correct it in worst points. I could understand the in those hose cases the flatness or parallelism we can the biggest absolute value between maxim and min label (to assure that from a theoretical mid position we get plan all plane points inside) but the current min / max label representation has no sense because always one out of them, will show a wrong value and bring confusion

[[Ma...]]

IF you want to show MIN and MAX, then don't do it on paralellism but try model comparison with selected faces ( triangles ) - it will show you MIN/MAX in selected alignment and with correct height.

Paralellism does not contain refference of height/distance

Edited Thursday at 09:09 AM