Strange problem with z axis in Marlin

Hi all, I have two days trying to find solution to this strange problem .

I have a Prusa air, working perfectly for 1 year. Ramps 1.4, sprinter and pronterface .

After reading several reviews I decided to change the firmware to marlin .

Everything, in principle , it works fine until I print.
Homing is made ​​perfectly and answering to commands, the coordinates are x 0 , y 0 , z 0 , and all endstops are depressed .

When printing works as usual. rises a little z axis, starts to move in x and y. As this occurs, the z axis starts to go down, scratching the surface of the base and starting to print 2 mm below the limit of endstop .

I have flashed different versions of Marlin, including the last from two weeks ago, obviously with the specs of my machine , and do all the same.

I have reviewed the Gcode of pronterface and everything is correct in the first layers

I have read countless post in English and Spanish and I have not been able to find a solution .....

Any ideas? ?

thanks

Quote
piogil


When printing works as usual. rises a little z axis, starts to move in x and y. As this occurs, the z axis starts to go down, scratching the surface of the base and starting to print 2 mm below the limit of endstop .

...

Any ideas? ?

thanks

Just a thought;
Have you by any chance set the Z offset in your slicing software? Sounds like that is what has happened or could be a work around if you haven't.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Hi regpye and thank for your thought

There is not option to offset axis in Pronterface..... or... I could not find it

The speed/acceleration for the Z axis was too high, so my Z axis was skipping steps on that upward move so that it is too low when it starts going back down.

I had the same problem after i moved from sprinter to marlin
butt in the other direction
I did not alterd the speed butt deleted the z axis 5down move
that seemd to do the trick to