i dont exactly know what a 3040 is, but if something is allowing that much movement i'd rather replace the thing causing the issue.. instead of losing all the travel would it not be better to start the gantry all over again and design it right so it doesnt flex? from a quick google it looks like its on rails.. would the next point of upgrade here be to replace them rails for supported ones? i'd imagine its the rail that bends and even if you double up it may still do it