So I would like to build a new printer. But I would like to use 4 z-axis motors. Do any of the 3d printer boards handle 4 z axis, 2 y axis and 1 x axis along with somewhere between 2 - 4 print heads. Also does merlin firmware even handle it ???

Thanks

You could bodge something up connecting the enable, step and dir pins for the z motor(s) from RAMPS for example to either 2or4 stepper drivers on some prototyping board. You don't need firmware support because they would all step at the same time. I say 2 or 4 because you could drive 2 motors from a single driver either in parallel or in series as is done by many printers now (mainly prusas and derivatives).

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Greg Frost
I say 2 or 4 because you could drive 2 motors from a single driver either in parallel or in series as is done by many printers now (mainly prusas and derivatives).

DRV8825 drivers are great for this: 2.2A with proper cooling. You could probably run 3 steppers off of one driver, if you do things right. Four off two would be a piece of cake.