Layer height in my cura settings means that head of extruder will be going up at 0.3mmm, and how i know that? Because i measure few different settings with height of bed.
When I set bed to -0.2mm, ike everybody is proposing on internet, and i started printing first layer, I did stop it and measure with precise caliper thickness, it was 4.2mm, (human precision with leveling bed :P ) that was for me to much, because extruded material almost was not sticking to the bed,, and walls was not connected each other.
I did test also with home position of nozzle and setting bed to touch nozzle, to 0 height. ( YEAH) And again I measure thickness of first layer. It was precise 0.3mm. Exactly as I want.
That means that or I have better software witch can take nozzle up with initial layer in cura settings?, or magical printer, but my printer is cheap and is buy'ed almost by everybody.
That means that peoples who are teaching others how to set bed in a printer are totally wrong. Maybe no one measure thickens of first layer?
Even seller from who I buy printer propose me use paper with thickens of 0.25mm to set level of the bed.
Previously I have problems with first layer, because that was too high from bed, now when I set 0 position of nozzle exactly with bed, I don't have problems with thickens of layer, and printed element looks allot better from bottom.