Y axis sag

[Art]

My rai;s (13') have some sag in them. It can be cured by installing a pair of adjustable legs in the center of the span. I would prefer to use a 12" vertical welded under the center and steel rod with turnbuckle attached to end of vertical and frame by legs. By tightening the rod in therory it should raise the center of rails. I would prefer to use this method so I can use the area under the indexer for storage.

[Gerald D]

I am looking at the pics on your website (http://www.turningaround.org/4_axis_mill.htm) to figure out
a. What material is under your "Y" rails? (I would call them x-rails)
b. How far apart the legs are now?
Can you maybe save me some guessing? :)

What is that red frame just below the rails - can that be used for stiffening?

[Art]

The rails are 4" by 4" and 13' between the legs. The red rail is one of the ways for the verticaly adjustable the A axis.

[Gerald D]

I wouldn't use tensioned truss rods. They could start resonating.

Another 4x4 under the first one, welded every foot, will make it about 8 times stiffer, if I remember the theory correctly.