Hello all. This is a very appealing site; I hope this first contribution of mine might interest someone. I was looking at the deflections of the column of my little X1 mill (Chester Cobra) the other day. The figures in the photo show the backward deflections when a standard force is applied to the top. The deflections are in 0.01 millimeters, when I pushed the top just enough to make the front of the machine base want to lift up.

Sure, some of that is just bending of the skinny column, but my impression was that it was not increasing as fast as you'd expect with height. A graph confirmed a substantial linear component, leading me to think it is pivoting backwards at the base.

More to see if I was right than to turn the X1 into a Bridgeport, I decided to use the upper and lower column tilt clamp bolts to rigidify the column base. Yes, the holes in the casting are slightly cockeyed, but never mind.

I used an extended lower bolt and a loose retaining plate at the bottom, and a substantial iron bar with bed iron supports at the top bolt. These aren't in the way of anything important, and a preliminary bit of blue paint even suggests original equipment.

The result? The green dots below. 44% reduction in movement, and the pivoting component has largely gone, as I hoped.

I don't know how much this improved rigidity buys me, but it somehow feels better, and this was pretty easy. The retaining plate contributes nearly half the improvement; I guess removing the tilt mechanism and reinforcing the column would do better, but I think that would be overkill for this machine.
Mark