XY calibration sheet graphic is confusing

[KickahaOta 14]

The text on the XY calibration sheet (both the old V1.5 version packed with my UM3 and the new V1.9 version that's for the S5 as well) does a pretty good job of explaining the operation clearly.

 

But I would say that the graphic showing you how to select a line actually confuses things again. The problem is that the difference in spacing between the Material 1 and Material 2 lines is much greater on the graphic than it is on an actual calibration print. So before I tried calibrating the real printer, when I looked at the graphic that was trying to show me 'See, choose +15 because that's perfectly lined up; don't pick -3 because that's off', my response was "Okay, but why wouldn't I choose -6? That's perfectly lined up too. Am I missing something? Would they both work?"

 

That situation -- two pairs of lines that are both perfect matches -- can't happen on the real calibration print (unless something is terribly off).

 

Is there a reason why the graphic takes this approach? Wouldn't it be better to use line spacing that better matches a real calibration print?

[gr5 2,172]

They would not both work.  You should choose -6 in the above case.  It is indeed a bad example.  You want to choose the closest value to zero which may be positive or it may be negative.  Typically it will always be less than 10.