Update README.md

Testcase added

README.md

@@ -2,3 +2,52 @@
 Personal tweaks and builds of marlin 3d printer firmware repositories.
 
 Source code is here: https://github.com/ThomasToka/MarlinbySynman/tree/bugfix-2.1.x-tweakedbyThomasToka
+
+Instructions: 
+
+Please do the following two tests:
+
+1.)
+- best is to start with leveled bed
+- flash the firmware 
+- reset to defaults via screen
+- heat up nozzle end bed to your desired temerature
+- g28
+- got to leveling on the screen
+- got to point 2
+- set initial z-offset on this point that it has a around 2mm clearance (this is not final leveling
+- go to points 3,4,5 an check if it nozzle to bed matches point 2, turn the wheels under bed to patch thos 2 mm..
+- go back to point 2, lower your z-offset to your desired height via screen (paper method, gauge, etc)
+- go to points 3,4,5 and adjust those with the wheels to match point 2
+- go around 2-3 times
+- do not touch point 1
+- go to leveling -> auto leveling, press start
+- after this your are ready to print
+- watch your g-code for the x position of your purge lines. your bad now starts exactly at x=0 and y=0
+
+2.)
+- best is to start with leveled bed
+- flash the firmware 
+- reset to defaults via screen
+- heat up nozzle end bed to your desired temerature
+- g28
+- got to leveling on the screen
+- got to point 1
+- set initial z-offset on this point that it has a around 2mm clearance (this is not final leveling
+- go to points 2,3,4,5 an check if it nozzle to bed matches point 1, turn the wheels under bed to patch those position..
+- go back to point 1, lower your z-offset to your desired height via screen (paper method, gauge, etc)
+- go to points 2,3,4,5 and adjust those with the wheels to match point 2
+- go around 2-3 times
+- do not touch point 1 after your can go around 2,3,4,5 with same height
+- go to leveling -> auto leveling, press start
+- after this your are ready to print
+- watch your g-code for the x position of your purge lines. your bad now starts exactly at x=0 and y=0
+
+What is interessting in those two tests:
+
+1) is your nozzle z-offset correct when the print starts on both?
+2) are there any differences between those two tests in the resulting shown z-offsets?
+
+Be carefully with your printer. Mine works fine. But this is a test. So have your fingers near the power button when lowering your z-axis.
+
+Please open an issue if there is something wrong.