I’m thinking 1000 mm x 1200 mm (or 1220 mm). My first set of linear rails were 1000 mm. After seeing that everything seems to fit, I’ll be more comfortable buying the ones that go length ways of the table (I call my Y axis). Since I have a pair of 4 ft SBK rails, I will probably install those to the underside of the gantry for additional support, as well as the linear rails on the side for the main support. I think I’m going to install 4, 6 inch legs of the 3030 beams to the corners and use my 1030 beams to support the table (which themselves will be supported by 4 feet which that should reinforce the inner part of the table.