If your slates are screwed down in the middle, were they crowned in the middle to begin with? Becasue that's the ONLY reason to have to add slate screws to the middle of the slates.Okay thanks for the info.
I will look into that app... that sounds interesting.
I was able to get 4x length but at break speed causing a jump off the rail.
the table has shims under the legs. the slate has screw in the middle to the frame.
I will look for any gaps.
solid wood frame with those blocks for the slate screws.