Printing problems

Hello,
i am working with a RepRap Prusa-Mendel 3DP01 and Repetier Host.
If i slice a programm and start it from a sd card the printer "drop" platic 11 cm obove the bed. He tried to print the Objekt from the other site (the lowest layer is the highest layer and the highest layer is the lowest layer and the objekt is flying in the air).
Sorry for my bad english.
I hope you can help me.
Max

Do you have limit switches on your printer's axes?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

yes, i have and he found his 0 point(start/homepoint), but then he start to print in the air.

So when you tell it to home it goes where it should but when printing it doesn't?
Check your slicer and make sure you didn't set a Z axis offset. that will cause the nozzle to rise before printing.
Look at the gcode and see where it thinks it's printing the first layer. If there's no z offset, early in the file you should see a command with a z axis value of 0.2 or whatever you set your first layer thickness to in the slicer.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I looked in the g-code and all is ok. I have to set the Slic3r, because if i say G1 Z5 , it is going 5 mm down.
My Z-sensor is at z = 119, but the chip thinks there is 0, so it tried to print it and only drop plastic 12 cm down.
I need to start printing at 0 (real coordinate, for mc...microcontroller 119) and then go up(mc... go down).
Which is the right setting, i tried a lot, but i did not find it.
Max

So it's an autoleveling issue- search the forum for fixes to that- there are a lot of people who have problems setting it up. I don't use it so I can't help with that one.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Ok thank you.
Max

Your description sounds like you have the printer homing to Zmax (as do I), but haven't configured the firmware to match. Which firmware are you using? If it's Marlin you need to set

#define Z_HOME_DIR 1

instead of -1 in Configuration.h, set Z_MAX_POS to accurately reflect the position above the bed when homed, and set MANUAL_Z_HOME_POS to Z_MAX_POS, e.g.

#define MANUAL_Z_HOME_POS Z_MAX_POS