You guys are a treasure
Your advices is for me GOLD
I go on with my plans. I add profiled rails and carriages ( downloaded from hiwin site). Before I go on with my gantry design I would like your opinion about the issues that I will come up with. What are the the points that I have to be careful. This is my progress

Click image for larger version. 

Name:	last.JPG 
Views:	2654 
Size:	287.0 KB 
ID:	11122

But I am wondering if the ballscrew sould be placed between the two 80X80 beams of the gantry, in front of Y axis (near z axis ) or in the back of Y axis. I also wonder about the best way to connect Y axis with X axis carriages.
Any idea will be helpful

Vagelis