Hi guys,
To clarify my point.
The plate is 27" x 48", the travels of the machine are 19.4" x 39.5"
The plate is shaped like a flat "U". I could mount it as a "U" or I could mount it as an upside down "U". It will mount to 6 rails of 1" x 3" 8020 extrusion which is on edge.
Regardless of which way I mount it, if I mill this on this machine, I will end up with what will look like a groove down the center along X axis that is .090" deep in the middle or at the ends. That groove will stop short of the ends by about 4.2" making it look like a pocket.
Bolting the 5/8" thick aluminum to the 8020 frame will most probably distort the frame, even if using shims.
No matter how I do it, it isn't the right way and it will look like a hack job.
If I have to spend $200 to get it straightened it is worth it to not have something that looks like a hack job.
With that said, I really do appreciate the suggestions, that is what makes this forum so good!
Chris D