Well Ive tried different things now.
The problem is: When using a higher first layer temperature the hotend expands or contracts depending on the temperature which is obvious ^^
Now when changing filament from say pet which only needs 210 deg. On the first layer to nylon which needs way over 250 deg. I need to readjust the z-stop. The heatbed tells the same story but its just a matter of some 1/100mm which is OK.
Who else has this problem?
if your slicer allows saving gcodes to profiles specific to filament you can always save different z offsets in your start code. I never adjust my physical switches anymore, the bed homes to the switches and then the actual position is set via gcode.
It’s less than a 50um difference between those two temperatures, probably closer to 10um - definitely noticeable, but also literally “just a matter of some 1/100mm”.
Using a different z-offset for each filament or generally a taller first layer height should take care of any issues.
@Thomas_Sanladerer well its a bit more on my e3d v6 than 50 microns. How can this be?
@VolksTrieb the hotend itself has no way of expanding more than this from a 40K temperate difference, so it has to be something else in the system if you’re seeing a significant difference of first layer to drop thickness. Have you stopped a print after the first layer and measured the thickness to get an accurate reading?
@Thomas_Sanladerer
Mhh well just calculated it out and your right. Well I dont understand it right now. Got some things printing right now…Gotta test it all
@Mark_Rehorst
No problems with sticking. Last thing i printed is 39.93mm-40.01mm which is ok (the filaprint isnt that perfectly flat.)
@Mark_Rehorst
Somehow when turning up the temperature the nozzle is closer to the bed. So much thou the first layer is not closed when printing at lower temperature.
@Mark_Rehorst during the print its not much of a problem rather than changing filament so changing the temperature
On top of what @Mark_Rehorst is saying, different hardnesses of filament have different hob bite depth, and thus have different effective E-steps/mm values. So if you change filament types without changing extrusion volume calibration, you’re going to over/under-extrude one of them (probably under-extrude the softer one I think)
@Mark_Rehorst @Ryan_Carlyle yep figured that out myself 
Got an exceltable of all my spools with diameter. And also when printing ABS the extrusionfactor is 0.925 and nylon is 0.915 where petg really works at 1. Not thats not the case. Either the bed warps or the hotend/construction of it does something. Need to investigate.
@Thomas_Sanladerer @Mark_Rehorst @Ryan_Carlyle
No idea why i didnt notice that but yeah its the heatbed. Ive got me an MK3 Alubed. Just so it wont warp but i believe its even more extreme than on a pcb one. Damnit! Any suggestions on what the best heatbed is? I thought of ceramic+silicone heater but cant find one. There is one for the renkforce RF1000 but its darn expensive…