For now I have a FL Sun Creality Chinese printer with 300x300 bed and a Z upt to 450mm upgrading to dual extruder direct feeder which is taking the extrusion head from 150 grams to 900 grams, imagine the vibrations at infill change of direction 5 times per second.
I am looking to make one with a bed 600 mm wide, 1800 mm wide, and 2000 mm on Z axis, where the bed is glass 10 mm thick, and will only move on Z axis, hence the Y and X will both be bounced at end of print by the heavy head, since I intend to go as close up as I can to 100 extruders in direct feed (the stepper that pushes the filament is right on top of the nozzle, hence filament in push I only have for 10 mm)
Physically this would destroy any structure even made in aviation steel.
I found a way around, that's not only multiple extruders, but placed on multiple carriers, so there will be 3 sides of the gantry beam (1 beneath and 2 left and right next to it), each gantry beam side will have 2 carriers, for a total of 6, each carrier can take some 10 to 16 extruders each.
The idea is to move the carriers of the same beam in the same time in opposite direction such that when they stop to return are doing it simultaneously thus cancelling reciprocally the stop and return generation momentum, but not ever banging against each other when traveling against the other.
All this on 3 sides of the beam in the same time, while each extruder is fed to fulfill the bit of slice task allocated.
Am I from a different planet?