Quote Originally Posted by D.C. View Post
It would seem to provide a far more rigid solution for any given weight when compared to the mdf/plywood/aluminium builds, am I missing something blindingly obvious or would this be worth pursuing?
Not quite blindingly obvious but this is one area lots don't fully under stand untill after they have used or seen the difference a heavy gantry makes.?

MASS makes a great deal of difference to the quality and depth of cut machine can make.! . . Yes a heavy gantry does slightly restrict rapid speeds compared to a light weight gantry but the reality is that most machines spend most of there time cutting not rapiding around. (Some exceptions do apply like drilling lots of holes)
So therefore the heavy stronger gantry with it's Mass can take far deeper cuts and still give a good finish and gets the Job done quicker than a light weight gantry can due to cutting deeper so less pass's.!
The Mass dampens vibration better and vib's transfer to the finish so again better finish.

Don't get caught up in the Rapid speed light weight race it's mainly for bragging rights and very little to do with useful cutting times and quality finish.

Also the doubling up of motors has very little to do with power to move a gantry and everything to do with ease of use and turning 2 screws to allow wide gantrys not to Rack or crab which they would with a single centre or side driven screw.
It's very possible and is often used to drive 2 screws with a single motor connected via timing belts and infact my machine use's just that setup. Timing belts are very accurate and efficient regards power usage and backlash etc so don't be put off using them.