This is just to let you control the first layer hight.

layer hight is 0.20 ( you can scale the part in your slicer to set it to the hight you need.
For first test its best to set the flow to a lower level so you get no over extrution becouse over extrution will get you the mesurment.
just print the file and mesure the tickness of the squares the should be 0.20 thick if this is correct your first layer hight is correct if not lets say if you messure 0.28 thickness you have to lower your Z axis 0.08 in the config or with the screws like you prefere.

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