Rostock Mini: Z-height issues

I've just finished building my first 3D printer, the Rostock Mini. Build the mechanics, made the default adjustments to the firmware to account for the mini-sizes and it does move in al the right ways. Joy there!

Next step would be te accuratly set the Z-height and start calibrating the buildplatform. However, when i tell it to travel 10mm down from home position it actually travels only 9mm. So instead of 200mm Z-travel i get 180mm.
This must be the steps/mm setting in Marlin but the strange thing is, it doesn't matter what number i give it (tried from calculated 44.44 up until an extreme 1000) but nothing changes.

What am i doing wrong?

I'm running on RAMPS 1.4 with Marlin firmware (june 7 release from jrocholl's github). Attached is a pic of the printer as is (no hot end attached yet).

Where are you changing the steps/mm?
If in the firmware are you uploading it AFTER making the changes.
If so and it still doesn't work do you perhaps have the EEPROM activated.
If so use the proper command to change the steps/mm in the EEPROM.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Thanx for youre reply!
I've changed it in the Arduino IDE and them uploaded it to the Arduino.
I'll have to find out what this EEPROM feature is. I'l look into it and see if that is causing the problem. Is it something i would want or better to disable it?

I don't use Marlin (or Repetier) firmware but I think the EEPROM feature is very useful as it allows you to change the settings on the fly without verifying/uploading the firmware!

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

If you are changing the source code and uploading and it still has no effect, then I'd bet that your EEPROM is activated. Once activated, it becomes the ONLY place your firmware gets its settings from.

The easiest way to make firmware changes is to use g code interactively to make the changes. If you like the new settings, you can then use g code again to commit those changes to EEPROM. If you want, you can also make the same changes in your source code, but this would only be for you to keep things straight.

The g code commands are: M201 through M205 for changing the values, and then M500 to store the values in EEPROM. If you want to abandon changes you have made and revert back to the stored EEPROM values, use M501.

A full g code reference can be found here.

Thanx guys! That worked. I did not know about that feature. I actually have it correctly going to the bed now. Still need to calibrate the flatness of the surface of course but were making progress.
Did a quicky with a pen and the standard 20mm cube test and it measured really well. Can't wait to make my first print. But i need to fix my extruder first but that's a different topic.

I've run into a little snag.
I'm trying to level the bed. Beneath the towers it's set correctly with the setscrews. I can just move a piece of paper between the nozzle and the bed but i feel it dragging a bit. So this is as it should be.
If i drop to Z0 in the center i slam into the bed. After carefully trying i found it is a bump of 0.9mm. The solution according to [minow.blogspot.nl] should be to decrease the DELTA_RADIUS by decreasing DELTA_SMOOTH_ROD_OFFSET.
The problem is that it doesn't matter if i change it from 138 to 100 or to 150. Nothing changes. EEPROM is still disabled so every time i change, save and re-upload it should be in the firmware (checked it with other settings and they do change).

What am i doing wrong?

Anybody? I'm stuck now and cannot continue.

Ok i've tried a lot of different things including completely replacing the firmware with the Repetier firmware and host. Unfortunalty that caused more problems so i'll leave that for now.
Since i seem to be the only one having this issue i'll post my config file here. Maybe i have some conflicting settings or something.
Could someone please have a look at it because i'm really stuck and baffled that it does not work.