Measument of printed object isnt like it supposed to be

After hours and hours making this prusa i3, finnaly everything seems to work except one thing...

I tryed to print case for my raspberry pi 2 and I made height of 10mm in modeling software, print it on CTC and everything is fine, then I tryed to print it as my first real print on my newly made Prusa i3 with auto bed leveling via servo near the nozzle and when print finished I noticed on first that height is to small so I measure it and it shows 5mm instead of 10mm, tryed again same result...?

Can someone help me to resolve this.

It is called calibration
You need to measure your movements and adjust the E stpes until they match perfectly, otherwise you will never get matching parts.

Thx allready doing it I didnt even calibrate z axis, whereever I looked and with reprap calculator all suggested z axis to be 4000 using m5 rod will try to see that cause x and y are perfect almost exact numbers except z axis 10mm object prints 5mm lower.... Wtf

WTF

Is it posiblle that in marlin I have 4000steps and when I move z axis by 10mm in pronterface z axis moves only 4.8mm so with this equation : 100/4.8 * 4000 I got 83333... Is that even posiblle...

EDIT: AM AN IDIOT 100 SHOULD BE IF I TRYED TO MOVE IT 100MM

Edited 1 time(s). Last edit at 01/26/2016 10:09AM by Beer4Brew.

So you got it right then?
I only take the calculators as a guid to get close to the real numbers.
The final tuning is done by checking the movements with calipers.

Yea I got it and now when I try to move 10mm from pronterface he moves it 10mm, I also needed to change movemment speed of z axis was 5mm now is 2mm.

I ended up with 2 more problems I cant make it to print from middle he prints a bit off and with extruding plastic doesnt get good prints, dont know how to center it but I know how to calibrate extruder, so if You have any idea about center issue You are more then welcome to help.

When I mark filament to 100mm and start extruding 100mm, mark shows that extruding isnt constant, extruder start extruding and continue to extrude by filament stops then continue again???

Check that your teeth in the drive gear are not full of chewed up plastic and that everything is tight and your motor drivers are set to the correct current.

Maybe the good old problem of a loose grub screw on the extruder?