So I had a thought when setting up a new cut job today. When holding the focusing tool in my hand I noticed one side has edges that are slightly raised. This is no doubt a result of the metal being sheared in the direction of the blade's travel when the metal was cut. If one places the tool with that side facing down and uses it to focus the laser it will place the laser at a higher level than doing it the other way around, This is because the raised edges will be contacting the backing plate, where if it was placed that side up the majority of the laser housing will be contacting the middle of the tool where it is perfectly flat, not at the edges. The difference is incredibly small; I measured the tool at 1.35mm in the middle and 1.46mm at the raised edge.
My question is: is that small difference enough to effect cuts/engravings? Which side would you recommend placing down?