Waste board or aluminum warped

So I’m building my new x-carve and I noticed that the waste board isn’t laying flat on the table. I put a flat bar across and there is a nice size gap at the middle suggesting that either the waste board is warped the aluminum rail is warped or both. Suggestions on how to correct this?

Hi Andrew, a few of us “resurface” our waste boards with a sacrificial waste board to resolve the issue. I use is a 0.5" bit. That way you know your work surface is parallel to your X and Y axis.

Start from the floor and work your way up. Don’t start with the wasteboard.

Is the floor flat? Use the longest metal straightedge you can find

Is the table flat? (flat from corner to corner, not level) If not, shim your legs

Are the aluminum extrusions perfectly straight?

Is the wasteboard flat?

I’m having issues with either a warped wasted board, or rails. Floor is level, and table top is flat and perfectly level. The whole thing rocks on top of the table. I’d appreciate any help or solutions