I worked on the table and there's just no salvaging it. I'm going to have to build another one. Not sure if I should go with 1 1/2" or 2" square tubing frame. Also, is MDF better than plywood as a top when it comes to warping with humidity?
MDF, with humidity and stress, curves; sealing/painting on all surfaces helps, but takes a LOT of paint. Marine plywood or
exterior-glue hardwood plywood is good, but the 'nice wood' face is thin, and will get some knocks from hunks of tooling.
You do NOT want soft wood products between the lathe and its supports. The tabletop should be considered a utility
shelf, not part of the structure.
Straight-grain wood, stressed along the grain, is stable enough to connect the
machine to the floor, and can be nailed/glued/bolted effectively (I'm not much of a welder). Then
there's truss plates... but Liquid Nails is more useful for DIY work.