Hi Vagelis,

I am a beginner here, so take my advice lightly!!
I have done a lot of reading and looking at other peoples designs.
Option 2: using two ballscrews with one motor sounds best to me. You can use the pulleys to gear the motor to your needs.

The other options means you have a ballscrew under the frame in the centre. this means you have to have 1500mm unsupported to allow the bridge to move.

people have sucessfully used both methods, but for a fixed amount of steel, option 2 allows for a stiffer frame. the relatively low cost of one extra ballscrew and pulleys/belts for me would be worth it.

Hopefully, more experienced people will offer their opinion for you.

good luck
greeny