Which rings just as bad. Steel is just as bad if not worse than aluminum.
None of the augmentations I have seen online will work. They all suffer from the same problem as the aluminum extrusion, lack of bracing.
The problem are the two inline bearings on the gantry. They flex like crazy. The aluminum the linear rails are fixed to is just the little ears in that slot.
What would work better for gantries this large are 4 bearings each side riding on two linear rails. Those rails attached to rigid frame would be the solution. So the Y axis bearings should be exactly like the X axis carriage but replace the 8020 with gray cast iron.
All of the examples I have seen online just replace the legs and leave that 8020 attached to the linear rails, which is the source of the flex and ringing.
I don’t expect everyone to own the equipment I do to test these things but it is actually easy to see by locking the steppers and just pushing on the gantry.
The legs are only 10% of the problem. The table is sturdy considering the 8020 it’s made from. The gantry is the problem, at least on my machine. Those rails flex and the aluminum with it.
EXTRA: there should be floating bearings too. Not having them builds oscillations in the system during high speed motion.