Focus test movement direction

I’m confused about just what direction my Z axes is moving ? I use a piece of dowel cut to aprox 50mm and drop the z until it touches the dowel, this I guess would be the starting point which when I get position shows up as 4.00 mm for Z. I use the black painted business cards I purchased for this test for use with a digital microscope. I have no problem getting it to run the test, I have it start at zero which I am assuming is my 4.00 mm start position and going to 4 (0-4) with say 10 intervals at 90% power and say 5 intervals. I get the thinest line is the third to the right of the start ! my question is, is it going from the start point in a downward direction , an upward direction or an upward and downward direction. In other words is it start halfway up fron the start and dropping halway below the start position. I have been scouring the internet trying to find a step by step explanation and no one seams to address this. There is a video by endurance lasers dong exactly this test, problem is this video like so many others is done by people who know what they are doing but don’t know how to dumb it down for new users.

sorry the intervals I set to start were 5 at 90% power

I’m not certain if I understand the exact nature of the confusion but I’ll try to offer what I understand of the test and hopefully it fills in the gaps.

  1. The Z-height distance values that are burned in the test reflect the actual relative height differences between the lines in the test.
  2. How you interpret the absolute height value of those lines is going to be determined by whether or not you have “Relative Z moves only” setting enabled in Device Settings.
    2a. If you do not have this set, then the numbers in the burn reflect the absolute Z-height. So in your example, after your initial focusing with the 50mm dowel, it would readjust to go to the starting height value.
    2b. If you have enabled this setting, then the values listed would be relative to your starting position. So values would be offset by your starting 50mm.

You should be able to physically observe this movement as the burn progresses. Perhaps setup a video camera that’s properly mounted and still and see how the laser head moves.