Microstepping driver A4988. Help

HI there fellow members! Im new too 3d printing.. And im building one.. One large printer.... ( 1200x1000x1000 mm large frame )

building with: Arduino Mega 2560, Ramps 1.4 and A4988 stepper driver. (Motor Nema 17 its a 3.1v 2.5 amps/phase 1.25 ohm 70oz/inch torque 1.8 step angle 2.5 amps [www.ebay.com])

Now too my question:

The current on the motor is 2.5 amp.. And my A4988 stepper says 2 amp maximum.. (Noticed this weeks after i bought the parts..)

Can i use this motor with the stepper i got? I mean.. Wont i fry it?

( or does the stepper only deliver a maximum 2 amp and a 2.5 amp motor is fine?)

If it would fry the steppers... Could i do something like limit the motors current? (Im not a brainiac..) Maybe put some resistense thingys?

Or maybe use a relay between the the electronics and the motor? So insted of power from the electronic it just controlls the relay and i supply the current trought the relay too the motor insted?..

Or should i just buy new steppers?

Thanks beforehand! Best regards /Patrik Sundén

A more realistic maximum for the A4988 stepper drivers is 1.2A. They will deliver the current you set them to, as long as they don't get too hot. So you can use them with your stepper motors, but you won't get the full torque out of them. You would be better using DRV8825 drivers such as these [www.pololu.com], which can deliver a little more current.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

@ dc42..

Thank you for your answer!

After reading your comment i came up with this: Ima hook everything up with the steppers i got so i can start too "program" or "code" or whatever you call it when you "program" your electronics (Arduino microkontrollers etc).

When i orderd the parts i wanted the most amp possible too the motor since i had no clue how much i really needed... (Going with a big, clumpsy and heavy build).


Since i wont "fry" my electronics ill go ahead with testing and programing

But ill order the steppers you recommended and install them before testing the motors under "load" (On the frame, going too test electronics loose on my desk before installing it too the frame).

Again.. Thank you for you answer! Best regards /Patrik Sundén