Accurate Strong Gantry

[vargai]

Might need to draw something up.

Tried to catch the principle based on sketches but this is more complex and one detail can change the others.
Here are some slightly more detailed plans -the C/G is near the C/L of the horizontal ball screw so hope this setup works.

That would naturally reduce the racking and take the pressure off the screws and rams.

I have increased the bearing spacing-350 mm now.I do not think it is worse than a moving gantry since it has double Z screw. Forces on screws mainly come from the vertical feed force -assuming it about 200 N(??) while I would like to reach 1000 N machining force in the horizontal plane.
If something might be considered to apply one more shorter Z rail and +1 each carriage on both side-I do not know if it worth
Drilling only means center drilling in this machine and max 6-8 mm holes. The machining that requires Z force will be arranged in the middle zone of the table where the load is almost symmetrical on screws

Regarding to the profile I started to change them to bend opened ones from 6-8 mm thickness. All of them havv to be designed according to their function

By the way when I am taking about balancing I am thinking of the Z motor too. I want it to get relieved form beam mass. It cannot be balanced perfectly since the spindle is moving but I want to remove the dead load expect the spindle at least.

This vertical in-between railing makes me worry a little.
The implementation will not be too easy. At the moment I am planing to put together the Z frame from three bolted parts