If it helps my machine has the same cutting area as yours and is R&P driven. I use the G540 on my machine.
It will rapid at 600ipm and cut at 200ipm, the limiting factor is the routers ability to cut at higher speed not the steppers ability to push it. The machine will cheerfully snap a 1/4" solid carbide cutter and not miss a step. I am running only 270ozin motors. My power supply is only 36 volts and it should be 48 volts to match the motors so they are underpowered at higher speeds.
I have seen video of a similar machine to mine with R&P drive using the G540 with 381ozin motors surface an 8' x 4' table with at 1000ipm.
The biggest motor you can put on the G540 is one that requires 50 volt at 3.5 Amp. The 381 ozin motor you have been looking at which I believe was made to match the G540.
So what are the advantages of large motors?
They are more expensive and require more expensive drivers to run them correctly.
They require larger more expensive power supplies.
Large motors have lower top end speeds and a properly geared small motor can out perform a larger stepper.
The larger the motor the more power you need to overcome the losses within the motor before you even start turning anything.
One of the biggest traps in selecting a stepper is the belief that bigger is better but it isn't true for steppers.
Personally I would go with the G540 option myself, but I'm bias
Cheers
Peter
The ingenuity of idiots is unlimited.
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