I’m looking to control 2 Stepper Motors in a CNC machine that are rated to the attached data sheet. The exact motors are the NEMA23’s.
I am using an ArduinoMega and want to move a carriage that, at max will be ~20 lbs. My desired speed range is from 3.5 mm/s to around 10 mm/s. I’ve been looking into Sparkfun’s “Big Easy Driver” but I believe these won’t give me the torque and speed I’m looking for because the max current isn’t anywhere near the nominal current for the steppers.
What components would I need to make the two motors run a carriage of that size at that speed? Would I need something like a Geckodrive? If anyone can give me a bit of guidance on how to choose the ideal driver for my desired outputs that would be helpful.
Big Easy Driver: https://www.sparkfun.com/products/11876
You need a stepper driver that can comfortably supply the current required by the motor. If the motor needs 4 amps I would go for a driver that can manage 5 or 6 amps. Remember that stepper motors draw their full current (or close to it) all of the time even when stationary.
Assuming you are using a high voltage power supply (i.e. well above the nominal voltage of the motor) your stepper driver needs to be able to limit the current to match the motor - otherwise the smoke will escape. You should use a high voltage for best performance.
You wil also need a power supply that can supply enough current. The motor rating is usually for a single coil so for 2 motors you may need a power supply capable of providing 4 * 4 = 16 amps - preferably more.
By the way I have no idea whether those motors are suitable for your project, or are underpowered or overpowered.
Nema23 is just the specification for the size of the front face of the motor - it says nothing about power.
I don't have high-current stepper myself but I have seen drivers for sale on Ebay that can control multiple motors and they seemed better value than several single drivers.
I believe these won't give me the torque and speed I'm looking for
Well, you haven't told us what you are looking for nor any sort of mechanical details. Screw drive? Gearbelt? Desired Feet Per Second? Distance?
Robin is of course correct in his recommendations IF you need the max power from those particular motors.