Solid build. Thanks for sharing it! I have been thinking about increasing my MiniMill's X to 500mm like you did. One question: is the plate with the larger MDF board stable enough?
It seems pretty stable. I haven't had time to use it until yesterday and cut this Jeep grill out of some pine. The MDF did flex a little when I was drilling the holes on the edge for the hold downs, but I won't be milling anything out that far.