Upgrading exsisting plasma table with aluminum extrusions or other ideas.

Hey everyone,

I have a small 4x2.5ft plasma I purchased this year. The gantry is made from a square tube and the torch mount runs along the 2x2 square tube via some angle aluminum and bearings plus a lead screw.

In a 4ft straight cut my edge is coming out as a wave. Highs and lows of 1/16 to 1/32 throughout the straight cut, which are in the same spots every time. This leads me to believe my gantry tube has a bit of a wave to it and my torch mount is following that wave.
I have been trying to come up with something to replace this tubing with that is much more precise. From my researching over the last few days I have discovered the extruded aluminum and linear rails with the bearing blocks that ride along them.

How straight is the extruded aluminum? I assume not very. I have also seen the precision ground stuff, which is another option if it solves my problem.

Open to other ideas of something I could use to replace the steel 2x2 square tube gantry to make my torch run much straighter.

Appreciate any help.