Cross post from discussion - Z Probe and first layer problems

Applerust

http://forum.repetier.com/discussion/1416/first-printer-layer-z-probe-offset-no-idea-what-to-do

Hey guys,

I have a friend that has been giving me a hand with setting up auto bed leveling and Repetier firmware.

The auto bed leveling works fine. My first layer consistently starts about
2mm above the bed (So, I'm printing in the air). We've changed several
settings and we end up getting the same results over and over.
Personally, I'm fed up with the entire process. I left Marlin behind to
be done with this exact issue and here we are again! lol

I'll paste my firmware here and hopefully someone can make some sense of it
and hopefully give me a hand. I'd greatly appreciate it, in fact!

I put it in pastebin (I think I did it right) please help!!!

Printer:
Mendel 90, 12V, HBP, Azteeg x3 pro board, Kraken hot end with only 2
nozzles setup, water cooled, using an induction sensor instead of a
servo and switch for the auto bed leveling routine.

http://pastebin.com/DH8iDj0A

Repetier

Solution is very easy.

Correct your z probe height by -2 mm. Alternatively increase zlength by 2mm after leveling.

3rd solution is change bed coating by 2mm also that is not what it was meant for. This requires coating set to measure real bed to work.

Applerust

My friend set this up almost entirely by himself. So, which of these do I alter?
Maybe:
#define Z_PROBE_Z_OFFSET 0


So, "#define Z_PROBE_Z_OFFSET -2.0"  ??

Repetier

Z offset is the be dcoating method, you should prevent. I meant

#define Z_PROBE_HEIGHT 22

or the equivalent in eeprom which is the value it really takes.

Applerust

In the firmware I changed
#define Z_PROBE_HEIGHT 22
To
#define Z_PROBE_HEIGHT 18
With no change in first layer print height. Then I did this:
#define Z_PROBE_HEIGHT 1
and again there was no change in the first layer print height. Absolutely no physical change has taken place and no other changes were made to the firmware other than this.

Applerust

Several individuals are suggesting I use "G92 Z2.0" to fix this issue but I want a solution that is based in the firmware. Why wouldn't changing the value of Z_PROBE_HEIGHThave any actual impact? What would prevent this from working properly?

Repetier

It does not change because you have eeprom enabled and eeprom has different values stored. Open eeprom in eeprom editor of our host/server and change the value there and you will see a difference.