Also, Why do you want a bigger print bed?
I have been working with a group of engineers designing and building a "Low cost professional quality heated chamber 3D printer" And by low cost, I really mean "LOW COST". (Aiming for 50% Ultimaker 2) We are pushing the boundary on "Minimum Viable Product" when it comes to professional quality 3D printer. We have our first rough prototype up and running, we started with a 250x250x300 build volume, but we now know this was a mistake, as there is never time to use that MASSIVE volume with a 0.4mm nozzle! The commercial products like the
Dimension uPrint have much more realistic volumes (203 x 152 x 152 mm). We have decided to build our second prototype with a 200x200x200 volume, which is still MASSIVE for high resolution prints. The only realistic way to print really large parts is with a LARGE nozzle... we have a LARGE printer with a 1.75mm nozzle hot end on the back burner... but to get these products ready for market takes many many man hours of hard work... we aren't there yet... but let me know if you want to be one of the first Beta tester's for a special price.