It occurs to me (as I'm sure it has to all of you) that there's no way it's going to get past even a meter before we start encountering structural issues. Plastic does not scale up all that well. Machining suddenly becomes a whole lot more important. We need a machine that can both print and machine with no structural changes, just a head swap. If we can print and machine, Simpson can continue to scale up.
edit: I'm going to admit I'm a bit biased towards a string-driven Simpson. That said, I think it would actual be easier to solve the problem of the drive pulley spinning than to use gears and have to solve backlash. I'm not sure but I think the strings should somewhat absorb vibrations. The elasticity on a spectra line is below 1%, but it IS slightly elastic.
edit2: Wait a second. Why would the drive pulley spin? Isn't the line permanently affixed to the pulleys, no friction necessary?
edit: I'm going to admit I'm a bit biased towards a string-driven Simpson. That said, I think it would actual be easier to solve the problem of the drive pulley spinning than to use gears and have to solve backlash. I'm not sure but I think the strings should somewhat absorb vibrations. The elasticity on a spectra line is below 1%, but it IS slightly elastic.
edit2: Wait a second. Why would the drive pulley spin? Isn't the line permanently affixed to the pulleys, no friction necessary?