Well I accomplished it today, well good enough anyways.
Perfect would of been 4 thicknesses of aluminum foil, I have 3, because I was to busy doing this...
I'm very happy with my Taig now, I tore it all apart and adjusted everything, 6 hours into it today, but it was worth it.
And to answer your question, the Z axis weight is a constant more or less, the flexing your talking about is something that will always be, but when not cutting we want it as perfect as can be, such as I have done, I'm now .0015" out of tram on the Y axis, I'm .0002" on the X axis, I was so happy with that I tack welded my column to my base. I was done messing with it.. you can only be so anal... Lol