Will I be killing the Pololu A4988?

Trying to build my first printer, I have 4 of the Pololu A4988, but the stepper motors I got are all rated 2.5A(u) . It is the wantai 42BYGHW811, 1.8deg/step. See image atached, I am using a 12Volt/30A power supply together with RAMPS 1.4. Can I go ahead powering the stepper motors using the A4988?.

no, you won’t kill your A4988, but you won’t get full torque out of your motor either.
The trimpot on the A4988 sets the current limit, anything over ~1.2A will overheat the A4988 with continuous use and no heatsink.
Symptoms are likely to be stuttering motion as the chip goes into thermal protection, then cools down and starts moving again.
Any print you’re doing will be shot by this phenomenon.


You might consider using our DRV8825 stepper motor driver as an alternative to the A4988. Although it would still not be able to handle the full current your stepper motor is able to draw, the DRV8825 can deliver 1.5 A per phase without a heat sink, and can be used as a drop-in replacement for the A4988 in many cases.


Thanks Guys, Once I am done building the printer, I will have to make a decision. The machine is Prusa I3, I do not reckon it needs much torque right?
Which is better,
1 Swapp the drivers or
2 Get less demanding stepper motors.

Eventually I need to do long run prints running into 16hrs!! or there about.

It sounds like you believe your application will not need all the power your motors can provide. If so, under powering the stepper motors might not be a problem. I suggest trying the parts you have to see if they will work. Just be sure to set the current limit to no more than the driver can handle.



I’m on a similar quest. I think it is a perfect way to get started: The “bigger” motors didn’t cost much extra, or cost just as much as the smaller ones would have cost.

Next we’ll start out with our project with the current limited at 1.0A or even lower, but with the option of upgrading that to achieve higher speeds eventually.

So… Set the current limit for something between 0.5 and 1A and get that machine working. Then continue to use it that way or upgrade when you want/need higher speeds.

(If for example, your 3D printer ends up waiting for the layer to cool before doing the next one, there is no point in making the motors go faster. )

Update: see A4988 doesn't microstep properly
if you want accurate microstepping… :frowning: