Hi there,
I am currently using four Big Easy stepper drivers (https://www.sparkfun.com/products/12859) to drive 4 filament extruders. They all receive the same STEP signal, while two receive a positive DIR and two receive a negative DIR.
The Big Easy stepper drivers have a rating of 2A/phase. Is it possible for me to replace these four Big Easy stepper drivers with a single stepper driver (such as https://www.robotshop.com/uk/phidgets-10-30v-8a-single-bipolar-stepper-motor-driver.html) which has a maximum of 8A per phase? Then I would split the each coil wire into four more wires to create four sets of four wires, with a set for each motor (and invert two sets for the motors spinning in the opposite direction).
To me this seems possible but I am new to electronics and wanted to make sure I am not doing something fundamentally incorrect. Thanks a lot for any advice. The reason for doing this is because currently I have to pass 16 cables through and I would like to be able to reduce that to only 4.
Hello @robot_cart
The solution you came up with could work as long as the driver can deliver enough current for the motors and the one you suggested is able to provide it, but there are a couple of things you should keep in mind and I think this post explains them well enough.
Also, notice the approach the person suggested at the end, you could hook the steppers up in series instead of in parallel (which is what you suggested), you can read more about this here.
I hope that information can help you out 
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That was very informative, thank you very much!
So even though the stepper drivers use a relatively high voltage, e.g. the BigEasy one uses 24V, the motors themselves only demand a low voltage such as 2V? And that is why even a smaller driver could power multiple motors in series? Does the driver require 24V in order for its electronics to work, or is it just to increase the maximum speed of the motors?
Again, thanks a lot 
You’re welcome 
Stepper drivers actually regulate the current supplied to the motors that is why you can drive the motors with a higher voltage. However, the rated voltage on the motors is just the voltage needed to provide the rated current when the motor is stationary. When the motor starts the back EMF will prevent the nominal voltage from producing the rated current. This is why stepper motors are normally driven with a much higher voltage and this why you need a specialized stepper motor driver like the BigEasy because it can limit the current to whatever the motor can take. If the current is not limited the high voltage would ruin the motor.
The BigEasy can work with 8-35V, it doesn’t need the power for its electronics to work but to give a better high-speed performance. You will actually get better performance by running at a higher voltage than the rated voltage.
You can find more information about stepper motors here and here.
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Don’t need to thank me haha I’m here to help
I looked at the motor driver you chose and everything seems good to me, you will have way more power and current than you need but since you are able to control how much current you will provide to the motors it is ok.
You should keep this in mind though
The choice of power supply voltage depends on the high-speed performance required of the motor; doubling the voltage doubles the motor’s high-speed power. In all cases, the power supply voltage should be no less than 4 times or no more than 25 times the motor’s rated voltage. The motor may not run as smoothly as possible if the power supply voltage is less than 4 times the motor’s rated voltage. A power supply voltage greater than 25 times the motor’s rated voltage will overheat and damage the motor, even if it is not turning.
Since you already have the motors you are going to use you could test how much voltage one of them needs to give a good performance and then multiply it by 4 (since you will use 4 motors) or maybe a little more and use that as a power supply, or if you don’t want to do that you could just approximate it to 4x2(rated voltage)x4(approx. - you could use anything under 25) = 32V+. I’m sure the motor controller you chose is able to handle that voltage because the power supply is up to 80V 
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Good luck with your project 
An easy way to drive multiple stepper drivers with one controller and very minimal wiring is to use I2C commanded stepper drivers. This requires only a 4 wire connection for all the controllers that can be daisy chained or wired in parallel to the controller.
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