I have always had problems with the y axis on my mega wilson, so I went back to the drawing board!
I liked the work @ant0ny was doing on some of his larger printers so I hit him up and we put together the following:
Twin SBR 12 UU supported rails, this time as wide as the table would allow.
350*430 y table, with 2 * lengths of 2020 on either side to support the heated bed.
The same 430*430 heated bed, with 240v silicon heater.
Over all it has been and astounding success, printing at 1000mm/s/s I get no y axis artifacts. Excuse the photos, the printer is sitting on the floor as it was shaking the sh$t out of my table.
Still left to do: the z axis uprights are currently supported by a loose piece of 2020 I'll do something more permanent.
I also need to add some stronger braces to the uprights the whole gantry now flexes by a couple of mm - probably just some metal corners. I am seeing some fairly minor X backlash artifacts.
Lithophane, petg, 0.1mm layer height, printed upright along the X axis.